diff --git a/backend/app/api/messages.py b/backend/app/api/messages.py
index 357340b..1cce5e0 100644
--- a/backend/app/api/messages.py
+++ b/backend/app/api/messages.py
@@ -11,7 +11,7 @@ from typing import Annotated
 from urllib.parse import quote
 
 from fastapi import APIRouter, Depends, Query
-from fastapi.responses import HTMLResponse, Response
+from fastapi.responses import FileResponse, HTMLResponse, Response
 from sqlalchemy import select
 from sqlalchemy.ext.asyncio import AsyncSession
 
@@ -33,6 +33,26 @@ DbSession = Annotated[AsyncSession, Depends(get_session)]
 # Content types safe to serve inline (SPEC §10.8); everything else is forced to
 # an attachment download with a neutral type.
 _INLINE_SAFE = {"image/png", "image/jpeg", "image/gif", "image/webp", "application/pdf"}
+# Videos the browser can play, by extension — senders often label them
+# application/octet-stream. A QuickTime .mov is usually H.264 in an MP4-style
+# container: offered as video/mp4, browsers play it (an HEVC one stays unplayable,
+# and the preview offers a download instead). Media cannot run script: safe inline.
+_VIDEO_EXT_MIME = {
+    "mp4": "video/mp4",
+    "m4v": "video/mp4",
+    "mov": "video/mp4",
+    "webm": "video/webm",
+    "ogv": "video/ogg",
+}
+
+
+def _inline_type(mime_type: str, filename: str) -> str | None:
+    """The type to serve an attachment as for in-app viewing, or None."""
+    if mime_type in _INLINE_SAFE:
+        return mime_type
+    ext = filename.rsplit(".", 1)[-1].lower() if "." in filename else ""
+    return _VIDEO_EXT_MIME.get(ext)
+
 
 # Base styles injected around the sanitized fragment so email content renders on a
 # readable light canvas with images that fit the pane (the iframe is sandboxed).
@@ -309,12 +329,15 @@ async def message_attachment(
     )
     if att is None:
         raise_api_error(404, "not_found", "attachment not found")
-    data = blobstore.load(msg.user_id, att.blob_sha256)
-    inline = att.mime_type in _INLINE_SAFE and not download
-    media_type = att.mime_type if inline else "application/octet-stream"
-    disposition = "inline" if inline else "attachment"
-    return Response(
-        content=data,
-        media_type=media_type,
+    path = blobstore.blob_path(msg.user_id, att.blob_sha256)
+    if not path.exists():
+        raise_api_error(404, "not_found", "attachment content missing")
+    inline_type = None if download else _inline_type(att.mime_type, att.filename)
+    disposition = "inline" if inline_type else "attachment"
+    # Streamed from disk, with HTTP Range: a video can be played and seeked
+    # without being sent whole first (Safari will not play one otherwise).
+    return FileResponse(
+        path,
+        media_type=inline_type or "application/octet-stream",
         headers={"Content-Disposition": _content_disposition(disposition, att.filename)},
     )
diff --git a/backend/app/indexer/mime.py b/backend/app/indexer/mime.py
index 7bab481..67fbb3e 100644
--- a/backend/app/indexer/mime.py
+++ b/backend/app/indexer/mime.py
@@ -139,6 +139,24 @@ def _extract_attachments(msg: EmailMessage) -> list[ParsedAttachment]:
                 payload=payload,
             )
         )
+    # An invitation sent only as the text/calendar alternative (Outlook, often) has
+    # no file to show: keep it as invite.ics, so the event can be seen, answered
+    # and downloaded like a Gmail one. Not when the message attaches its own .ics.
+    if not any(a.filename.lower().endswith(".ics") for a in out):
+        for part in msg.walk():
+            if part.get_content_type() != "text/calendar" or part.get_filename():
+                continue
+            payload = part.get_payload(decode=True)
+            if isinstance(payload, bytes) and payload.strip():
+                out.append(
+                    ParsedAttachment(
+                        filename="invite.ics",
+                        mime_type="text/calendar",
+                        content_id=None,
+                        payload=payload,
+                    )
+                )
+                break
     return out
 
 
diff --git a/backend/app/plugins/actions.py b/backend/app/plugins/actions.py
index e937f5e..7468fd0 100644
--- a/backend/app/plugins/actions.py
+++ b/backend/app/plugins/actions.py
@@ -24,7 +24,7 @@ from sqlalchemy import select
 from app.db import session_scope
 from app.events import get_event_bus
 from app.indexer import blobstore
-from app.models import Account, Mailbox, Message, Thread
+from app.models import Account, Mailbox, Message, Thread, User
 
 
 class PluginMessages:
@@ -163,13 +163,10 @@ class PluginMessages:
 
 
 class PluginAccounts:
-    """Cross-user account queries, for scheduled jobs.
-
-    Deliberately not user-scoped: a sweep runs on behalf of the instance, not a
-    request, and needs to find work across every user. Nothing here returns
-    content — only ids and state — so a plugin still has to go through the
-    user-scoped accessors to read anything.
-    """
+    """Account queries: ``live()`` is cross-user, for scheduled jobs (a sweep runs
+    on behalf of the instance and returns only ids and state); ``of_user`` and
+    ``settings_of`` read one user's own accounts and settings, for a handler
+    already acting as that user."""
 
     async def live(self) -> list[tuple[uuid.UUID, uuid.UUID]]:
         """``(user_id, account_id)`` for every account finished with its initial
@@ -181,6 +178,23 @@ class PluginAccounts:
             )
             return [(u, a) for u, a in rows]
 
+    async def of_user(self, user_id: uuid.UUID) -> list[tuple[uuid.UUID, str, str]]:
+        """``(account_id, email, display_name)`` of the user's own mail accounts —
+        e.g. to tell which attendee of an emailed invitation is the user."""
+        async with session_scope() as session:
+            rows = await session.execute(
+                select(Account.id, Account.email, Account.display_name)
+                .where(Account.user_id == user_id)
+                .order_by(Account.created_at)
+            )
+            return [(a, str(e), str(n or "")) for a, e, n in rows]
+
+    async def settings_of(self, user_id: uuid.UUID) -> dict[str, object]:
+        """The user's settings (time zone, default calendar, …), read-only."""
+        async with session_scope() as session:
+            settings = await session.scalar(select(User.settings).where(User.id == user_id))
+            return dict(settings or {})
+
 
 class PluginThreads:
     """Read-only, user-scoped thread queries (e.g. self-healing stale references)."""
diff --git a/backend/tests/api/test_api.py b/backend/tests/api/test_api.py
index f84588c..3bdfc6d 100644
--- a/backend/tests/api/test_api.py
+++ b/backend/tests/api/test_api.py
@@ -605,3 +605,40 @@ async def test_attachment_thumbnails(api: ApiCtx) -> None:
 
     assert (await api.client.get(url("notes.txt"))).status_code == 404
     assert (await api.client.get(url("broken.jpg"))).status_code == 404
+
+
+async def test_video_attachment_streams_with_range(api: ApiCtx) -> None:
+    # A video plays in the preview: served inline as video (whatever the sender
+    # called it) and in pieces on request (HTTP Range), so it can be seeked.
+    from app.indexer import blobstore
+    from app.models import Attachment
+
+    assert api.session is not None
+    mid = api.message_ids[-1]
+    data = bytes(range(256)) * 40  # 10 240 bytes standing in for a video
+    att = Attachment(
+        message_id=mid,
+        user_id=api.user_id,
+        filename="clip.MOV",
+        mime_type="application/octet-stream",
+        size_bytes=len(data),
+        content_id=None,
+        blob_sha256=blobstore.store(api.user_id, data),
+    )
+    api.session.add(att)
+    await api.session.commit()
+    url = f"/api/messages/{mid}/attachments/{att.id}"
+
+    whole = await api.client.get(url)
+    assert whole.status_code == 200 and whole.content == data
+    assert whole.headers["content-type"] == "video/mp4"
+    assert whole.headers["content-disposition"].startswith("inline")
+    assert whole.headers["accept-ranges"] == "bytes"
+
+    part = await api.client.get(url, headers={"Range": "bytes=1000-1999"})
+    assert part.status_code == 206 and part.content == data[1000:2000]
+    assert part.headers["content-range"] == f"bytes 1000-1999/{len(data)}"
+
+    saved = await api.client.get(url + "?download=1")
+    assert saved.headers["content-type"] == "application/octet-stream"
+    assert saved.headers["content-disposition"].startswith("attachment")
diff --git a/backend/tests/plugins/test_calendar_invitations.py b/backend/tests/plugins/test_calendar_invitations.py
new file mode 100644
index 0000000..b98acb4
--- /dev/null
+++ b/backend/tests/plugins/test_calendar_invitations.py
@@ -0,0 +1,256 @@
+"""Calendar plugin: invitations received by email (iMIP) — the reading-pane card
+and Yes / No / Maybe, through the real HTTP surface.
+
+A Gmail-style invitation (text/calendar METHOD:REQUEST + an invite.ics file) is
+stored as a real message; answering must put the event in the calendar (or take
+it out) and send the organizer an iTIP REPLY. Outgoing mail is captured, not sent.
+"""
+
+from __future__ import annotations
+
+import uuid
+from collections.abc import AsyncIterator
+from dataclasses import dataclass, field
+from datetime import UTC, datetime
+from email.message import EmailMessage
+
+import httpx
+import pytest_asyncio
+from httpx import ASGITransport
+from sqlalchemy import delete, text
+from sqlalchemy.ext.asyncio import async_sessionmaker, create_async_engine
+from sqlalchemy.pool import NullPool
+
+from app.config import get_settings
+from app.identity.passwords import hash_password
+from app.identity.sessions import create_session
+from app.indexer.indexer import persist_message
+from app.indexer.mime import parse_message
+from app.main import create_app
+from app.models import Account, Mailbox, User
+from app.plugins import mail as plugin_mail
+from app.providers.base import RemoteMessage
+
+CAL = "/api/plugins/calendar"
+ME = "me@example.com"
+ORGANIZER = "boss@example.org"
+
+
+def _ics(method: str = "REQUEST", attendees: tuple[str, ...] = (ME,), seq: int = 0) -> str:
+    people = "".join(
+        f"ATTENDEE;CN=Guest;PARTSTAT=NEEDS-ACTION;RSVP=TRUE:mailto:{a}\r\n" for a in attendees
+    )
+    return (
+        "BEGIN:VCALENDAR\r\nPRODID:-//Google Inc//Google Calendar 70.9054//EN\r\n"
+        f"VERSION:2.0\r\nMETHOD:{method}\r\n"
+        "BEGIN:VEVENT\r\n"
+        "DTSTART;TZID=Europe/Warsaw:20261007T133000\r\n"
+        "DTEND;TZID=Europe/Warsaw:20261007T143000\r\n"
+        "DTSTAMP:20261006T183413Z\r\n"
+        f"ORGANIZER;CN=The Boss:mailto:{ORGANIZER}\r\n"
+        "UID:test-invite-1@google.com\r\n"
+        f"{people}"
+        "X-GOOGLE-CONFERENCE:https://meet.google.com/abc-defg-hij\r\n"
+        "LOCATION:Gliwice\r\n"
+        f"SEQUENCE:{seq}\r\nSTATUS:{'CANCELLED' if method == 'CANCEL' else 'CONFIRMED'}\r\n"
+        "SUMMARY:Maintenance Renewal\r\nEND:VEVENT\r\nEND:VCALENDAR\r\n"
+    )
+
+
+def _email(ics: str, method: str) -> bytes:
+    m = EmailMessage()
+    m["Subject"] = "Invitation: Maintenance Renewal"
+    m["From"] = f"The Boss <{ORGANIZER}>"
+    m["To"] = ME
+    m["Message-ID"] = f"<{uuid.uuid4()}@example.org>"
+    m.set_content("You have been invited.")
+    m.add_alternative("<p>You have been invited.</p>", subtype="html")
+    m.add_alternative(ics, subtype="calendar", params={"method": method})
+    m.make_mixed()
+    m.add_attachment(ics.encode(), maintype="application", subtype="ics", filename="invite.ics")
+    return m.as_bytes()
+
+
+@dataclass
+class Ctx:
+    user_id: uuid.UUID
+    client: httpx.AsyncClient
+    sm: async_sessionmaker  # type: ignore[type-arg]
+    account_id: uuid.UUID
+    mailbox_id: uuid.UUID
+    sent: list[dict[str, object]] = field(default_factory=list)
+    uid: int = 0
+
+    async def message(self, raw: bytes) -> str:
+        self.uid += 1
+        async with self.sm() as s:
+            result = await persist_message(
+                s,
+                user_id=self.user_id,
+                account_id=self.account_id,
+                mailbox_id=self.mailbox_id,
+                mailbox_special_use="inbox",
+                remote=RemoteMessage(
+                    uid=self.uid, raw=raw, flags=frozenset(), internal_date=datetime.now(UTC)
+                ),
+            )
+            await s.commit()
+        assert result is not None
+        return str(result.message.id)
+
+
+@pytest_asyncio.fixture
+async def ctx(monkeypatch) -> AsyncIterator[Ctx]:  # type: ignore[no-untyped-def]
+    engine = create_async_engine(get_settings().database_url, poolclass=NullPool)
+    sm = async_sessionmaker(engine, expire_on_commit=False)
+    async with sm() as s:
+        user = User(
+            handle=f"inv{uuid.uuid4().hex[:8]}@test.local", password_hash=hash_password("pw")
+        )
+        s.add(user)
+        await s.flush()
+        account = Account(
+            user_id=user.id,
+            email=ME,
+            display_name="Me Myself",
+            imap_config={"host": "imap.example.com", "port": 993, "tls": "ssl"},
+            smtp_config={"host": "smtp.example.com", "port": 465, "tls": "ssl"},
+            secret_ct=b"",
+            discovery_src="manual",
+            state="live",
+        )
+        s.add(account)
+        await s.flush()
+        inbox = Mailbox(account_id=account.id, user_id=user.id, path="INBOX", special_use="inbox")
+        s.add(inbox)
+        await s.commit()
+        ids = (user.id, account.id, inbox.id)
+    token = await create_session(ids[0], "pytest")
+    client = httpx.AsyncClient(
+        transport=ASGITransport(app=create_app()),
+        base_url="http://testserver",
+        cookies={"session": token, "csrf": "csrf"},
+        headers={"X-CSRF": "csrf"},
+    )
+    c = Ctx(user_id=ids[0], client=client, sm=sm, account_id=ids[1], mailbox_id=ids[2])
+
+    async def fake_send(self, user_id, **kw):  # type: ignore[no-untyped-def]
+        c.sent.append(kw)
+
+    monkeypatch.setattr(plugin_mail.PluginMail, "send", fake_send)
+    try:
+        yield c
+    finally:
+        await client.aclose()
+        async with sm() as s:
+            await s.execute(
+                text("DELETE FROM plg_calendar_calendars WHERE user_id = :u"), {"u": str(ids[0])}
+            )
+            await s.execute(delete(User).where(User.id == ids[0]))
+            await s.commit()
+        await engine.dispose()
+
+
+async def _calendar_events(c: Ctx) -> list[dict[str, object]]:
+    r = await c.client.get(
+        f"{CAL}/events", params={"start": "2026-10-07T00:00:00Z", "end": "2026-10-08T00:00:00Z"}
+    )
+    return r.json()["events"]
+
+
+async def test_invitation_card_and_answers(ctx: Ctx) -> None:
+    mid = await ctx.message(_email(_ics(), "REQUEST"))
+
+    # Something already in the calendar at that time: a conflict.
+    cal_id = (await ctx.client.get(f"{CAL}/calendars")).json()[0]["id"]
+    await ctx.client.post(
+        f"{CAL}/events",
+        json={
+            "calendar_id": cal_id,
+            "summary": "Design review",
+            "dtstart": "2026-10-07T11:00:00Z",  # 13:00 in Warsaw
+            "dtend": "2026-10-07T12:00:00Z",
+        },
+    )
+
+    card = (await ctx.client.get(f"{CAL}/invitations/{mid}")).json()
+    assert card["method"] == "REQUEST" and card["summary"] == "Maintenance Renewal"
+    assert card["start"] == "2026-10-07T13:30:00+02:00" and card["tz"] == "Europe/Warsaw"
+    assert card["organizer"] == {"email": ORGANIZER, "name": "The Boss"}
+    assert card["location"] == "Gliwice"
+    assert card["conference_url"] == "https://meet.google.com/abc-defg-hij"
+    assert card["me"]["email"] == ME and card["response"] == "needs-action"
+    assert card["in_calendar"] is None
+    assert [c["summary"] for c in card["conflicts"]] == ["Design review"]
+
+    # Yes: in the calendar, and the organizer gets an iTIP REPLY.
+    r = await ctx.client.post(f"{CAL}/invitations/{mid}/respond", json={"response": "accepted"})
+    assert r.status_code == 200
+    card = r.json()
+    assert card["response"] == "accepted" and card["in_calendar"]["calendar"] == "Personal"
+    assert card["reply_sent"] is True
+    reply = ctx.sent[-1]
+    assert reply["to"] == [ORGANIZER] and reply["from_email"] == ME
+    assert reply["ics_method"] == "REPLY" and reply["subject"] == "Accepted: Maintenance Renewal"
+    ics = str(reply["ics"])
+    assert "METHOD:REPLY" in ics and "UID:test-invite-1@google.com" in ics
+    assert "PARTSTAT=ACCEPTED" in ics and f"mailto:{ME}" in ics
+    events = [e for e in await _calendar_events(ctx) if e["summary"] == "Maintenance Renewal"]
+    assert len(events) == 1 and events[0]["my_partstat"] == "accepted"
+
+    # Maybe: the same event, answer updated.
+    r = await ctx.client.post(f"{CAL}/invitations/{mid}/respond", json={"response": "tentative"})
+    assert r.json()["response"] == "tentative" and "PARTSTAT=TENTATIVE" in str(ctx.sent[-1]["ics"])
+    events = [e for e in await _calendar_events(ctx) if e["summary"] == "Maintenance Renewal"]
+    assert len(events) == 1 and events[0]["my_partstat"] == "tentative"
+
+    # No: out of the calendar — and still shown as the answer given.
+    r = await ctx.client.post(f"{CAL}/invitations/{mid}/respond", json={"response": "declined"})
+    assert r.json()["in_calendar"] is None and "PARTSTAT=DECLINED" in str(ctx.sent[-1]["ics"])
+    assert r.json()["response"] == "declined"
+    assert (await ctx.client.get(f"{CAL}/invitations/{mid}")).json()["response"] == "declined"
+    assert not [e for e in await _calendar_events(ctx) if e["summary"] == "Maintenance Renewal"]
+
+    # Changing one's mind back to Yes: in the calendar again, "No" forgotten.
+    r = await ctx.client.post(f"{CAL}/invitations/{mid}/respond", json={"response": "accepted"})
+    assert r.json()["response"] == "accepted" and r.json()["in_calendar"] is not None
+
+
+async def test_cancelled_event_is_removed(ctx: Ctx) -> None:
+    invite = await ctx.message(_email(_ics(), "REQUEST"))
+    await ctx.client.post(f"{CAL}/invitations/{invite}/respond", json={"response": "accepted"})
+    cancel = await ctx.message(_email(_ics("CANCEL", seq=1), "CANCEL"))
+
+    card = (await ctx.client.get(f"{CAL}/invitations/{cancel}")).json()
+    assert card["method"] == "CANCEL" and card["in_calendar"] is not None
+    # A cancellation cannot be answered, only taken out of the calendar.
+    no = await ctx.client.post(f"{CAL}/invitations/{cancel}/respond", json={"response": "accepted"})
+    assert no.status_code == 400
+    card = (await ctx.client.post(f"{CAL}/invitations/{cancel}/remove")).json()
+    assert card["in_calendar"] is None
+    assert not [e for e in await _calendar_events(ctx) if e["summary"] == "Maintenance Renewal"]
+
+
+async def test_not_invited_or_not_an_invitation(ctx: Ctx) -> None:
+    other = await ctx.message(_email(_ics(attendees=("someone@else.com",)), "REQUEST"))
+    card = (await ctx.client.get(f"{CAL}/invitations/{other}")).json()
+    assert card["me"] is None  # forwarded to the user, say: nothing to answer
+    r = await ctx.client.post(f"{CAL}/invitations/{other}/respond", json={"response": "accepted"})
+    assert r.status_code == 400
+
+    plain = EmailMessage()
+    plain["Subject"], plain["From"], plain["To"] = "Hello", ORGANIZER, ME
+    plain.set_content("Just a note.")
+    mid = await ctx.message(plain.as_bytes())
+    assert (await ctx.client.get(f"{CAL}/invitations/{mid}")).status_code == 404
+
+
+def test_outlook_style_invitation_is_kept_as_a_file() -> None:
+    # Outlook often sends the calendar only as the text/calendar alternative:
+    # the indexer keeps it as invite.ics, so the card has something to find.
+    m = EmailMessage()
+    m["Subject"], m["From"], m["To"] = "Meeting", ORGANIZER, ME
+    m.set_content("plain")
+    m.add_alternative(_ics(), subtype="calendar", params={"method": "REQUEST"})
+    files = parse_message(m.as_bytes()).attachments
+    assert [(a.filename, a.mime_type) for a in files] == [("invite.ics", "text/calendar")]
diff --git a/frontend/src/components/Toast.tsx b/frontend/src/components/Toast.tsx
new file mode 100644
index 0000000..4fe973c
--- /dev/null
+++ b/frontend/src/components/Toast.tsx
@@ -0,0 +1,44 @@
+import { useEffect, useState } from "react";
+
+// A short confirmation in the corner — the Undo-send toast's look, without the
+// button. Raised by anything (core or a plugin bundle) with
+//   window.dispatchEvent(new CustomEvent("webmail:toast", { detail: { text } }))
+// e.g. "Reply sent" after answering an invitation. Gone after a few seconds.
+const SHOW_MS = 3500;
+
+export function Toast({ mobile }: { mobile: boolean }) {
+  const [toast, setToast] = useState<{ text: string; seq: number } | null>(null);
+
+  useEffect(() => {
+    let timer: number | undefined;
+    let seq = 0;
+    const onToast = (e: Event) => {
+      const text = (e as CustomEvent<{ text?: string }>).detail?.text;
+      if (!text) return;
+      setToast({ text, seq: ++seq });
+      window.clearTimeout(timer);
+      timer = window.setTimeout(() => setToast(null), SHOW_MS);
+    };
+    window.addEventListener("webmail:toast", onToast);
+    return () => {
+      window.removeEventListener("webmail:toast", onToast);
+      window.clearTimeout(timer);
+    };
+  }, []);
+
+  if (!toast) return null;
+  return (
+    <div
+      key={toast.seq}
+      role="status"
+      className={
+        mobile
+          ? // Level with the Compose button on the other side of the screen.
+            "fixed bottom-[calc(4.375rem+env(safe-area-inset-bottom))] left-4 z-40 flex h-11 items-center rounded-xl bg-app-fg px-4 text-[15px] font-medium text-app-surface shadow-lg"
+          : "fixed bottom-4 right-4 z-50 flex w-80 items-center rounded-lg bg-app-fg px-4 py-2.5 text-sm text-app-surface shadow-lg"
+      }
+    >
+      {toast.text}
+    </div>
+  );
+}
diff --git a/frontend/src/components/list/MessageList.tsx b/frontend/src/components/list/MessageList.tsx
index a576586..ced0be6 100644
--- a/frontend/src/components/list/MessageList.tsx
+++ b/frontend/src/components/list/MessageList.tsx
@@ -5,6 +5,7 @@ import { useEffect, useRef } from "react";
 import { useT } from "../../i18n";
 import { api } from "../../lib/api";
 import { useListDividers } from "../../lib/listDividers";
+import { avatarColor } from "../../lib/avatarColor";
 import { useSavedThreads } from "../../lib/offline";
 import { formatClock, getDateLocale } from "../../lib/timeFormat";
 import type { Address, ThreadSummary } from "../../lib/types";
@@ -22,12 +23,6 @@ function timeLabel(iso: string): string {
 }
 
 // Stable per-sender hue so a sender's avatar keeps a consistent colour.
-function hue(key: string): number {
-  let h = 0;
-  for (let i = 0; i < key.length; i++) h = (h * 31 + key.charCodeAt(i)) % 360;
-  return h;
-}
-
 function initials(p: Address | undefined): string {
   const name = (p?.name || p?.email || "?").trim();
   const words = name.split(/\s+/).filter(Boolean);
@@ -187,7 +182,7 @@ export function MessageList({
           // The badge still counts everyone involved — the name is narrowed, the
           // "how many people are in this" signal is not.
           const extra = Math.max(0, thread.participants.length - 1);
-          const avatarBg = `hsl(${hue(primary?.email || primary?.name || "?")} 45% 45%)`;
+          const avatarBg = avatarColor(primary?.email, primary?.name, accounts.data);
           const stop = (fn: () => void) => (e: React.MouseEvent) => {
             e.stopPropagation();
             fn();
diff --git a/frontend/src/components/mail/RightPanel.tsx b/frontend/src/components/mail/RightPanel.tsx
index 82467b9..8388208 100644
--- a/frontend/src/components/mail/RightPanel.tsx
+++ b/frontend/src/components/mail/RightPanel.tsx
@@ -9,8 +9,9 @@ import { lazy, Suspense, useEffect, useMemo, useRef, useState } from "react";
 import { useNavigate } from "react-router-dom";
 
 import { useT } from "../../i18n";
+import { avatarColor } from "../../lib/avatarColor";
 import { api, apiFetch } from "../../lib/api";
-import type { Address, AttachmentOut, MessageEnvelope, ThreadDetail } from "../../lib/types";
+import type { AttachmentOut, MessageEnvelope, ThreadDetail } from "../../lib/types";
 import { AvatarImage } from "../SenderAvatar";
 import { useIsMobile } from "../../lib/useIsMobile";
 import { loadBundle } from "../../plugins/bundleLoader";
@@ -27,22 +28,17 @@ const AttachmentPreview = lazy(() =>
 export type PanelTab = "calendar" | "people" | "attachments";
 
 // ---- small helpers ---------------------------------------------------------
-const AV_COLORS = ["#ef4444", "#f97316", "#eab308", "#22c55e", "#14b8a6", "#3b82f6", "#8b5cf6", "#ec4899", "#6b7280"];
-function avatarColor(key: string) {
-  let h = 0;
-  for (const c of key || "?") h = (h * 31 + c.charCodeAt(0)) >>> 0;
-  return AV_COLORS[h % AV_COLORS.length];
-}
 function initials(name: string) {
   const p = (name || "").trim().split(/\s+/).filter(Boolean);
   if (!p.length) return "?";
   return ((p[0][0] || "") + (p.length > 1 ? p[p.length - 1][0] : "")).toUpperCase();
 }
 function Avatar({ name, email, size = 36 }: { name: string; email: string; size?: number }) {
+  const accounts = useQuery({ queryKey: ["accounts"], queryFn: api.accounts });
   return (
     <span
       className="relative inline-flex shrink-0 items-center justify-center overflow-hidden rounded-full font-semibold text-white"
-      style={{ width: size, height: size, background: avatarColor(email || name), fontSize: Math.round(size * 0.38) }}
+      style={{ width: size, height: size, background: avatarColor(email, name, accounts.data), fontSize: Math.round(size * 0.38) }}
     >
       {initials(name || email)}
       <AvatarImage email={email} />
@@ -184,14 +180,23 @@ function PeopleTab({ thread, onInviteAll }: { thread: ThreadDetail | undefined;
   const [openEmail, setOpenEmail] = useState<string | null>(null);
   const [openName, setOpenName] = useState("");
 
-  // "In conversation" = unique senders from the open thread.
+  // "In conversation" = everyone in the open thread — who wrote it, and who it
+  // went to (To, Cc, Bcc: e.g. whom a message was forwarded to), the user
+  // included. Each person once, under the name any message gives them, A–Z.
   const convPeople = useMemo(() => {
-    const seen = new Map<string, Address>();
+    const names = new Map<string, string>();
     for (const m of thread?.messages ?? []) {
-      const a = m.from_addr[0];
-      if (a?.email && !seen.has(a.email.toLowerCase())) seen.set(a.email.toLowerCase(), a);
+      for (const a of [...m.from_addr, ...m.to_addr, ...m.cc_addr, ...m.bcc_addr]) {
+        const key = a?.email?.toLowerCase();
+        if (!key) continue;
+        // Some messages carry the address itself as the name: that is no name.
+        const name = a.name && a.name.toLowerCase() !== key ? a.name : "";
+        if (!names.get(key)) names.set(key, name);
+      }
     }
-    return [...seen.values()].map((a) => ({ id: "", display_name: a.name || a.email, primary_email: a.email }));
+    return [...names.entries()]
+      .map(([email, name]) => ({ id: "", display_name: name || email, primary_email: email }))
+      .sort((a, b) => a.display_name.localeCompare(b.display_name, undefined, { sensitivity: "base" }));
   }, [thread]);
 
   const groups = useQuery({ queryKey: ["contact-groups"], queryFn: () => apiFetch<Group[]>("/plugins/contacts/groups"), enabled: source === "autosaved" });
@@ -213,6 +218,24 @@ function PeopleTab({ thread, onInviteAll }: { thread: ThreadDetail | undefined;
     return <PersonDetail email={openEmail} name={openName} onBack={() => setOpenEmail(null)} />;
   }
 
+  const personRow = (p: { display_name: string; primary_email: string }) => (
+    <button
+      key={p.primary_email}
+      className="flex w-full items-center gap-3 px-4 py-2 text-left hover:bg-app-hover"
+      onClick={() => {
+        setOpenName(p.display_name);
+        setOpenEmail(p.primary_email);
+      }}
+    >
+      <Avatar name={p.display_name} email={p.primary_email} />
+      <div className="min-w-0 flex-1">
+        <div className="truncate font-medium">{p.display_name}</div>
+        <div className="truncate text-[13px] text-app-muted">{p.primary_email}</div>
+      </div>
+      <svg width="16" height="16" viewBox="0 0 16 16" fill="none" stroke="currentColor" strokeWidth="1.6" className="text-app-faint"><path d="M6 4l4 4-4 4" /></svg>
+    </button>
+  );
+
   const SOURCES: [PeopleSource, string][] = [
     ["conversation", t("panel.inConversation")],
     ["all", t("panel.allContacts")],
@@ -260,20 +283,10 @@ function PeopleTab({ thread, onInviteAll }: { thread: ThreadDetail | undefined;
         </div>
       </div>
 
-      <div className="px-3 py-2 text-[12px] font-semibold uppercase tracking-wide text-app-faint">{t("panel.senders")}</div>
       {people.length === 0 ? (
         <div className="px-4 py-6 text-sm text-app-faint">{t("panel.noPeople")}</div>
       ) : (
-        people.map((p, i) => (
-          <button key={p.primary_email + i} className="flex w-full items-center gap-3 px-4 py-2 text-left hover:bg-app-hover" onClick={() => { setOpenName(p.display_name); setOpenEmail(p.primary_email); }}>
-            <Avatar name={p.display_name} email={p.primary_email} />
-            <div className="min-w-0 flex-1">
-              <div className="truncate font-medium">{p.display_name}</div>
-              <div className="truncate text-[13px] text-app-muted">{p.primary_email}</div>
-            </div>
-            <svg width="16" height="16" viewBox="0 0 16 16" fill="none" stroke="currentColor" strokeWidth="1.6" className="text-app-faint"><path d="M6 4l4 4-4 4" /></svg>
-          </button>
-        ))
+        people.map((p) => personRow(p))
       )}
     </div>
   );
@@ -316,7 +329,6 @@ function PersonDetail({ email, name, onBack }: { email: string; name: string; on
         </div>
         <div className="mt-4 flex justify-around">
           <ActionBtn label={t("panel.call")} disabled={!c?.phones?.length} onClick={() => c?.phones?.[0] && window.open(`tel:${c.phones[0].value}`)} icon={<svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="1.7" strokeLinecap="round" strokeLinejoin="round"><path d="M4 4h4l2 5-3 2a12 12 0 0 0 6 6l2-3 5 2v4a2 2 0 0 1-2 2A16 16 0 0 1 2 6a2 2 0 0 1 2-2" /></svg>} />
-          <ActionBtn label={t("panel.message")} onClick={() => navigate(`/mail?compose=1&to=${encodeURIComponent(primary)}`)} icon={<svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="1.7" strokeLinecap="round" strokeLinejoin="round"><path d="M21 15a2 2 0 0 1-2 2H8l-4 4V5a2 2 0 0 1 2-2h13a2 2 0 0 1 2 2z" /></svg>} />
           <ActionBtn label={t("panel.compose")} onClick={() => navigate(`/mail?compose=1&to=${encodeURIComponent(primary)}`)} icon={<svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="1.7" strokeLinecap="round" strokeLinejoin="round"><path d="M12 20h9" /><path d="M16.5 3.5a2.1 2.1 0 0 1 3 3L7 19l-4 1 1-4z" /></svg>} />
           <ActionBtn label={t("panel.invite")} onClick={() => window.open(`/p/calendar?guest=${encodeURIComponent(primary)}`, "_blank", "noopener")} icon={<svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="1.7" strokeLinecap="round" strokeLinejoin="round"><rect x="3" y="4" width="18" height="18" rx="2" /><path d="M16 2v4M8 2v4M3 10h18" /></svg>} />
         </div>
diff --git a/frontend/src/components/thread/AttachmentPreview.tsx b/frontend/src/components/thread/AttachmentPreview.tsx
index 23d2743..775df1b 100644
--- a/frontend/src/components/thread/AttachmentPreview.tsx
+++ b/frontend/src/components/thread/AttachmentPreview.tsx
@@ -147,15 +147,17 @@ export function AttachmentPreview({
           </span>
         </div>
         <div className="flex items-center gap-1">
-          <button
-            type="button"
-            onClick={printAtt}
-            title={t("mail.print")}
-            aria-label={t("mail.print")}
-            className="rounded p-1.5 text-white/80 hover:bg-white/10 hover:text-white"
-          >
-            <Icon name="print" size={19} />
-          </button>
+          {kind !== "video" && (
+            <button
+              type="button"
+              onClick={printAtt}
+              title={t("mail.print")}
+              aria-label={t("mail.print")}
+              className="rounded p-1.5 text-white/80 hover:bg-white/10 hover:text-white"
+            >
+              <Icon name="print" size={19} />
+            </button>
+          )}
           <button
             type="button"
             onClick={download}
@@ -174,11 +176,12 @@ export function AttachmentPreview({
       <div
         className="relative min-h-0 flex-1"
         onClick={(e) => {
-          if (!(e.target as Element).closest("img, iframe, canvas, pre, button, a, form, input"))
+          if (!(e.target as Element).closest("img, video, iframe, canvas, pre, button, a, form, input"))
             onClose();
         }}
       >
         {kind === "image" && <ImageView url={url} zoom={zoom} alt={att.filename} />}
+        {kind === "video" && <VideoView key={att.id} url={url} onDownload={download} />}
         {kind === "text" && (
           <TextView url={url} zoom={zoom} onLoaded={(tx) => (textRef.current = tx)} />
         )}
@@ -208,8 +211,8 @@ export function AttachmentPreview({
         )}
       </div>
 
-      {/* Bottom controls */}
-      <div className="flex shrink-0 items-center justify-center py-3">
+      {/* Bottom controls (a video has its own, in the player) */}
+      <div className={`flex shrink-0 items-center justify-center py-3 ${kind === "video" ? "hidden" : ""}`}>
         <div className="flex items-center gap-2 rounded-full bg-black/60 px-3 py-1.5 text-sm text-white ring-1 ring-white/15">
           {kind === "pdf" && page.total > 0 && (
             <>
@@ -270,6 +273,41 @@ function ZoomButton({ onClick, label }: { onClick: () => void; label: string })
   );
 }
 
+// A video, in the browser's own player. A format it cannot play (an HEVC .mov,
+// say) says so and offers the download instead of a dead black box.
+function VideoView({ url, onDownload }: { url: string; onDownload: () => void }) {
+  const t = useT();
+  const [failed, setFailed] = useState(false);
+  if (failed) {
+    return (
+      <div className="flex h-full w-full flex-col items-center justify-center gap-3 text-white/80">
+        <span>{t("mail.previewVideoUnsupported")}</span>
+        <button
+          type="button"
+          onClick={onDownload}
+          className="rounded-md bg-white/15 px-3 py-1.5 text-sm text-white hover:bg-white/25"
+        >
+          {t("mail.download")}
+        </button>
+      </div>
+    );
+  }
+  return (
+    <div className="flex h-full w-full items-center justify-center p-4">
+      {/* Paused until the user plays it. The #t fragment makes browsers that
+          would otherwise show black (Safari) fetch and show the first frame. */}
+      <video
+        src={`${url}#t=0.001`}
+        controls
+        playsInline
+        preload="metadata"
+        onError={() => setFailed(true)}
+        className="max-h-full max-w-full rounded bg-black shadow-2xl"
+      />
+    </div>
+  );
+}
+
 function ImageView({ url, zoom, alt }: { url: string; zoom: number; alt: string }) {
   return (
     <div className="flex h-full w-full items-center justify-center overflow-auto p-4">
diff --git a/frontend/src/components/thread/Attachments.tsx b/frontend/src/components/thread/Attachments.tsx
index 877dd2f..64df152 100644
--- a/frontend/src/components/thread/Attachments.tsx
+++ b/frontend/src/components/thread/Attachments.tsx
@@ -6,7 +6,7 @@ import spreadsheetSvgRaw from "../../../icons/spreadsheet.svg?raw";
 import { useT } from "../../i18n";
 import { api } from "../../lib/api";
 import type { AttachmentOut } from "../../lib/types";
-import { extOf, isPreviewable } from "./previewKind";
+import { extOf, isPreviewable, VIDEO_EXT } from "./previewKind";
 
 // These icons carry their own (baked-in) colours via inline styles, so render
 // them raw rather than through <Icon>, which strips styles. Drop the XML prolog.
@@ -75,8 +75,25 @@ const ARCHIVE_EXT = new Set(["zip", "rar", "7z", "tar", "gz", "bz2", "xz"]);
 const SPREADSHEET_EXT = new Set(["xlsx", "ods"]);
 const DOC_EXT = new Set(["txt", "docx", "odt"]); // blue document icon
 
+// Video: a film frame with a play triangle.
+function VideoGlyph() {
+  return (
+    <svg width="26" height="26" viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="1.5" strokeLinejoin="round" aria-hidden>
+      <rect x="3" y="5" width="18" height="14" rx="2" />
+      <path d="M10 9.2v5.6l4.8-2.8z" fill="currentColor" />
+    </svg>
+  );
+}
+
 function AttachmentIcon({ filename }: { filename: string }) {
   const e = extOf(filename);
+  if (VIDEO_EXT.has(e)) {
+    return (
+      <span className="shrink-0 text-violet-500">
+        <VideoGlyph />
+      </span>
+    );
+  }
   if (e === "pdf") {
     return (
       <span className="shrink-0 text-red-600 dark:text-red-500">
diff --git a/frontend/src/components/thread/ThreadView.tsx b/frontend/src/components/thread/ThreadView.tsx
index 662b4e2..9138cce 100644
--- a/frontend/src/components/thread/ThreadView.tsx
+++ b/frontend/src/components/thread/ThreadView.tsx
@@ -2,6 +2,7 @@ import { useMutation, useQuery, useQueryClient } from "@tanstack/react-query";
 import { Fragment, useEffect, useMemo, useRef, useState } from "react";
 
 import { useT } from "../../i18n";
+import { personHue } from "../../lib/avatarColor";
 import { api } from "../../lib/api";
 import { printMessages } from "../../lib/print";
 import { useIsMobile } from "../../lib/useIsMobile";
@@ -98,10 +99,7 @@ function initials(msg: MessageEnvelope): string {
 
 // Stable per-sender hue so a sender's avatar + name share a colour (like the mockup).
 function hue(msg: MessageEnvelope): number {
-  const key = (msg.from_addr[0]?.email || msg.from_addr[0]?.name || "?").toLowerCase();
-  let h = 0;
-  for (let i = 0; i < key.length; i++) h = (h * 31 + key.charCodeAt(i)) % 360;
-  return h;
+  return personHue(msg.from_addr[0]?.email || msg.from_addr[0]?.name || "?");
 }
 
 function fmtRelative(iso: string): string {
@@ -493,7 +491,10 @@ function MessageItem({
             </div>
           </div>
           {/* Plugin-contributed per-message banner (SPEC §11.3 message.banner). */}
-          <PluginSlot name="message.banner" props={{ messageId: message.id }} />
+          <PluginSlot
+            name="message.banner"
+            props={{ messageId: message.id, hasAttachments: message.has_attachments }}
+          />
           <div className="px-4 pb-3">
             <MessageBody message={message} onMailto={onMailto} />
           </div>
diff --git a/frontend/src/components/thread/previewKind.ts b/frontend/src/components/thread/previewKind.ts
index 86b862d..0c2ea14 100644
--- a/frontend/src/components/thread/previewKind.ts
+++ b/frontend/src/components/thread/previewKind.ts
@@ -2,6 +2,8 @@
 // clickability without pulling the heavy preview bundle (lazy-loaded on open).
 
 const IMAGE_EXT = new Set(["jpg", "jpeg", "png", "gif", "webp"]);
+// Played in the preview's <video> (the server serves these inline, with Range).
+export const VIDEO_EXT = new Set(["mp4", "m4v", "mov", "webm", "ogv"]);
 // Office docs converted to HTML client-side (docx via mammoth, ODF via JSZip).
 const OFFICE_EXT = new Set(["docx", "xlsx", "odt", "ods", "odp", "odg"]);
 
@@ -11,15 +13,16 @@ export function extOf(name: string): string {
 
 export function isPreviewable(name: string): boolean {
   const e = extOf(name);
-  return e === "pdf" || e === "txt" || IMAGE_EXT.has(e) || OFFICE_EXT.has(e);
+  return e === "pdf" || e === "txt" || IMAGE_EXT.has(e) || OFFICE_EXT.has(e) || VIDEO_EXT.has(e);
 }
 
-export type PreviewKind = "image" | "pdf" | "text" | "office";
+export type PreviewKind = "image" | "pdf" | "text" | "office" | "video";
 
 export function kindOf(name: string): PreviewKind {
   const e = extOf(name);
   if (e === "pdf") return "pdf";
   if (e === "txt") return "text";
   if (OFFICE_EXT.has(e)) return "office";
+  if (VIDEO_EXT.has(e)) return "video";
   return "image";
 }
diff --git a/frontend/src/i18n/en.ts b/frontend/src/i18n/en.ts
index 2b95dc3..49a86da 100644
--- a/frontend/src/i18n/en.ts
+++ b/frontend/src/i18n/en.ts
@@ -95,6 +95,7 @@ export const en = {
   "mail.expandAll": "Expand all",
   "mail.collapseAll": "Collapse all",
   "mail.print": "Print",
+  "mail.previewVideoUnsupported": "This video can't be played in the browser.",
   "mail.previewPage": "Page {current} / {total}",
   "mail.previewResetZoom": "Reset zoom",
   "mail.previewPrev": "Previous",
@@ -169,7 +170,6 @@ export const en = {
   "panel.composeAll": "Compose to all",
   "panel.inviteAll": "Invite all to new event",
   "panel.call": "Call",
-  "panel.message": "Message",
   "panel.compose": "Compose",
   "panel.invite": "Invite",
   "panel.contactDetails": "Contact details",
diff --git a/frontend/src/lib/avatarColor.ts b/frontend/src/lib/avatarColor.ts
new file mode 100644
index 0000000..485bea3
--- /dev/null
+++ b/frontend/src/lib/avatarColor.ts
@@ -0,0 +1,23 @@
+// One colour per person, the same wherever their initials circle appears —
+// the mail list, the reading pane, the People tab. The user's own accounts use
+// the colour chosen for the account; anyone else a stable hue from their address.
+
+import type { AccountOut } from "./types";
+
+export function personHue(key: string): number {
+  const k = (key || "?").toLowerCase();
+  let h = 0;
+  for (let i = 0; i < k.length; i++) h = (h * 31 + k.charCodeAt(i)) % 360;
+  return h;
+}
+
+/** Background of a person's initials circle. */
+export function avatarColor(
+  email: string | null | undefined,
+  name: string | null | undefined,
+  accounts: AccountOut[] | undefined,
+): string {
+  const key = (email || "").toLowerCase();
+  const own = key ? accounts?.find((a) => a.email.toLowerCase() === key) : undefined;
+  return own?.color ?? `hsl(${personHue(email || name || "?")} 45% 45%)`;
+}
diff --git a/frontend/src/routes/MailLayout.tsx b/frontend/src/routes/MailLayout.tsx
index 2896abf..3fd15c9 100644
--- a/frontend/src/routes/MailLayout.tsx
+++ b/frontend/src/routes/MailLayout.tsx
@@ -7,6 +7,7 @@ import { AppSwitcher } from "../components/AppSwitcher";
 import { ComposeDock } from "../components/compose/ComposeDock";
 import { Composer, type ComposerInit, draftToInit, localToInit } from "../components/compose/Composer";
 import { UndoSendToast } from "../components/compose/UndoSendToast";
+import { Toast } from "../components/Toast";
 import { usePendingSend } from "../components/compose/undoSend";
 import {
   collapseExpanded,
@@ -1530,6 +1531,7 @@ export function MailLayout() {
         fullScreen={mobile}
       />
       <UndoSendToast mobile={mobile} onUndone={reopenUnsent} />
+      <Toast mobile={mobile} />
     </div>
   );
 }
diff --git a/plugins/webmail_plugin_calendar/pyproject.toml b/plugins/webmail_plugin_calendar/pyproject.toml
index 4b9f9d6..2a8018c 100644
--- a/plugins/webmail_plugin_calendar/pyproject.toml
+++ b/plugins/webmail_plugin_calendar/pyproject.toml
@@ -21,4 +21,4 @@ calendar = "webmail_plugin_calendar:plugin"
 packages = ["webmail_plugin_calendar"]
 
 [tool.setuptools.package-data]
-webmail_plugin_calendar = ["ui/*.js", "migrations/versions/*.py"]
+webmail_plugin_calendar = ["ui/*.js", "ui/*.svg", "migrations/versions/*.py"]
diff --git a/plugins/webmail_plugin_calendar/webmail_plugin_calendar/__init__.py b/plugins/webmail_plugin_calendar/webmail_plugin_calendar/__init__.py
index f051b8e..369b29f 100644
--- a/plugins/webmail_plugin_calendar/webmail_plugin_calendar/__init__.py
+++ b/plugins/webmail_plugin_calendar/webmail_plugin_calendar/__init__.py
@@ -3,15 +3,15 @@
 A **core, non-removable** plugin (``builtin=True``) that ships a `/calendar` page
 beside Mail. Its own ``plg_calendar_*`` tables (RLS-isolated) hold calendars and
 events; recurrence is expanded at query time. Uses the SDK only — zero core diffs.
-Phase A1 (local events) is the current scope; iMIP (A2) and CalDAV/ICS (A3) build
-on the same data model and the SDK's vault + multi-method HTTP.
+Local events (A1), iMIP invitations sent and received (A2) and CalDAV / ICS (A3)
+share one data model, the SDK's vault and its multi-method HTTP.
 """
 
 from __future__ import annotations
 
 from pathlib import Path
 
-from app.plugins.sdk import JobSpec, Page, PageNav, Plugin, UiManifest
+from app.plugins.sdk import JobSpec, Page, PageNav, Plugin, Slot, UiManifest
 from webmail_plugin_calendar.router import router
 from webmail_plugin_calendar.sync import caldav_sync
 
@@ -25,6 +25,9 @@ plugin = Plugin(
     jobs=[JobSpec(func=caldav_sync, schedule="*/15 * * * *")],
     router=router,
     ui_manifest=UiManifest(
+        # An invitation received by email, above the message body (iMIP): renders
+        # only for a message carrying an .ics, so ordinary mail shows nothing.
+        slots=[Slot(name="message.banner", bundle="/api/plugins/calendar/ui/invite.js")],
         pages=[
             Page(
                 route="/calendar",
diff --git a/plugins/webmail_plugin_calendar/webmail_plugin_calendar/imip.py b/plugins/webmail_plugin_calendar/webmail_plugin_calendar/imip.py
new file mode 100644
index 0000000..2b3a020
--- /dev/null
+++ b/plugins/webmail_plugin_calendar/webmail_plugin_calendar/imip.py
@@ -0,0 +1,188 @@
+"""Invitations received by email (iMIP, RFC 6047 / iTIP, RFC 5546).
+
+An invitation is an email carrying a ``text/calendar; method=REQUEST`` part (or
+``CANCEL`` when the organizer calls the event off). ``calendar_part`` finds it,
+``parse_invite`` turns its event into what the reading pane shows and the
+calendar stores, and ``build_reply`` makes the ``METHOD:REPLY`` the organizer's
+calendar (Google, Outlook, …) reads to record the answer.
+"""
+
+from __future__ import annotations
+
+import email
+import re
+from datetime import UTC, date, datetime, timedelta
+from email import policy
+from typing import Any
+from zoneinfo import ZoneInfo, ZoneInfoNotFoundError
+
+# Google wraps its Meet details in this block; it means nothing elsewhere.
+_GOOGLE_BLOCK = re.compile(r"-::~[:~]*::-.*?-::~[:~]*::-", re.S)
+_PARTSTATS = {"accepted", "declined", "tentative", "needs-action"}
+
+
+def calendar_part(raw: bytes) -> str | None:
+    """The calendar data of an email: its inline ``text/calendar`` part (the one
+    carrying METHOD), else an attached ``.ics``. None for any other email."""
+    msg = email.message_from_bytes(raw, policy=policy.default)
+    attached: str | None = None
+    for part in msg.walk():
+        ctype = part.get_content_type()
+        name = (part.get_filename() or "").lower()
+        if ctype not in ("text/calendar", "application/ics") and not name.endswith(".ics"):
+            continue
+        payload = part.get_payload(decode=True)
+        if not isinstance(payload, bytes):
+            continue
+        text = payload.decode(part.get_content_charset() or "utf-8", "replace")
+        if ctype == "text/calendar" and not part.get_filename():
+            return text
+        attached = attached or text
+    return attached
+
+
+def _address(prop: Any) -> dict[str, str] | None:
+    if prop is None:
+        return None
+    addr = str(prop)
+    email_addr = addr[7:] if addr.lower().startswith("mailto:") else addr
+    name = str(prop.params.get("CN", "")).strip() if hasattr(prop, "params") else ""
+    email_addr = email_addr.strip().lower()
+    # Some senders put the address itself in CN: that is no name.
+    return {"email": email_addr, "name": "" if name.lower() == email_addr else name}
+
+
+def _zone(start_prop: Any, start: date | datetime) -> str:
+    """The event's IANA time zone (for recurrence and display), else UTC."""
+    candidates = [str(start_prop.params.get("TZID", ""))] if hasattr(start_prop, "params") else []
+    if isinstance(start, datetime) and start.tzinfo is not None:
+        zone = getattr(start.tzinfo, "key", "") or getattr(start.tzinfo, "zone", "")
+        candidates.append(str(zone))
+    for name in candidates:
+        if not name:
+            continue
+        try:
+            ZoneInfo(name)
+            return name
+        except (ZoneInfoNotFoundError, ValueError):
+            continue
+    return "UTC"
+
+
+def _moment(value: date | datetime, tz: str, all_day: bool) -> datetime:
+    if all_day or not isinstance(value, datetime):
+        d = value if not isinstance(value, datetime) else value.date()
+        return datetime(d.year, d.month, d.day, tzinfo=UTC)
+    if value.tzinfo is None:  # floating time: read it in the event's zone
+        return value.replace(tzinfo=ZoneInfo(tz))
+    return value
+
+
+def parse_invite(ics: str) -> dict[str, Any] | None:
+    """The event an invitation is about, or None if there is none."""
+    from icalendar import Calendar
+
+    try:
+        cal = Calendar.from_ical(ics)
+    except Exception:  # noqa: BLE001 - malformed calendar data: no invitation
+        return None
+    events = list(cal.walk("VEVENT"))
+    if not events:
+        return None
+    # A series with changed occurrences: the series itself (no RECURRENCE-ID).
+    comp = next((e for e in events if e.get("recurrence-id") is None), events[0])
+    start_prop = comp.get("dtstart")
+    if start_prop is None:
+        return None
+    start = start_prop.dt
+    all_day = not isinstance(start, datetime)
+    tz = _zone(start_prop, start)
+    dtstart = _moment(start, tz, all_day)
+    end_prop = comp.get("dtend")
+    if end_prop is not None:
+        dtend = _moment(end_prop.dt, tz, all_day)
+    elif comp.get("duration") is not None:
+        dtend = dtstart + comp.get("duration").dt
+    else:
+        dtend = dtstart + (timedelta(days=1) if all_day else timedelta(hours=1))
+    recurrence = comp.get("recurrence-id")
+    rrule = comp.get("rrule")
+    attendees = []
+    raw_attendees = comp.get("attendee") or []
+    for prop in raw_attendees if isinstance(raw_attendees, list) else [raw_attendees]:
+        who = _address(prop)
+        if who is None or not who["email"]:
+            continue
+        stat = str(prop.params.get("PARTSTAT", "NEEDS-ACTION")).lower()
+        who["partstat"] = stat if stat in _PARTSTATS else "needs-action"
+        attendees.append(who)
+    description = _GOOGLE_BLOCK.sub("", str(comp.get("description") or "")).strip()
+    location = str(comp.get("location") or "").strip()
+    conference = str(comp.get("x-google-conference") or "").strip()
+    if not conference and location.startswith(("https://meet.", "https://teams.", "https://zoom.")):
+        conference = location
+    return {
+        "method": str(cal.get("method") or "REQUEST").upper(),
+        "uid": str(comp.get("uid") or ""),
+        "sequence": int(comp.get("sequence") or 0),
+        "summary": str(comp.get("summary") or ""),
+        "description": description,
+        "location": location,
+        "conference_url": conference,
+        "dtstart": dtstart,
+        "dtend": dtend,
+        "all_day": all_day,
+        "tz": tz,
+        "rrule": rrule.to_ical().decode() if rrule is not None else None,
+        "recurrence_id": _moment(recurrence.dt, tz, all_day) if recurrence is not None else None,
+        "status": str(comp.get("status") or "confirmed").lower(),
+        "organizer": _address(comp.get("organizer")),
+        "attendees": attendees,
+        "show_as": "free" if str(comp.get("transp") or "").upper() == "TRANSPARENT" else "busy",
+    }
+
+
+_REPLY_WORD = {"accepted": "Accepted", "declined": "Declined", "tentative": "Tentatively accepted"}
+
+
+def reply_subject(partstat: str, summary: str) -> str:
+    return f"{_REPLY_WORD.get(partstat, 'Reply')}: {summary}"
+
+
+def build_reply(ics: str, me: dict[str, str], partstat: str) -> str:
+    """The ``METHOD:REPLY`` telling the organizer ``me`` answered ``partstat``:
+    the invitation's own event identity (UID, SEQUENCE, times, RECURRENCE-ID)
+    with just the replying attendee, as RFC 5546 asks."""
+    from icalendar import Calendar, Event, vCalAddress
+
+    source = Calendar.from_ical(ics)
+    events = list(source.walk("VEVENT"))
+    original = next((e for e in events if e.get("recurrence-id") is None), events[0])
+    cal = Calendar()
+    cal.add("prodid", "-//Ultimo//Calendar//EN")
+    cal.add("version", "2.0")
+    cal.add("method", "REPLY")
+    for tz in source.walk("VTIMEZONE"):
+        cal.add_component(tz)
+    ev = Event()
+    keep = (
+        "uid",
+        "sequence",
+        "dtstart",
+        "dtend",
+        "duration",
+        "recurrence-id",
+        "summary",
+        "organizer",
+    )
+    for key in keep:
+        if original.get(key) is not None:
+            ev[key] = original[key]
+    ev.add("dtstamp", datetime.now(UTC))
+    attendee = vCalAddress(f"mailto:{me['email']}")
+    attendee.params["PARTSTAT"] = partstat.upper()
+    if me.get("name"):
+        attendee.params["CN"] = me["name"]
+    ev.add("attendee", attendee)
+    cal.add_component(ev)
+    return cal.to_ical().decode()
diff --git a/plugins/webmail_plugin_calendar/webmail_plugin_calendar/invites.py b/plugins/webmail_plugin_calendar/webmail_plugin_calendar/invites.py
index 281471e..a5f8a77 100644
--- a/plugins/webmail_plugin_calendar/webmail_plugin_calendar/invites.py
+++ b/plugins/webmail_plugin_calendar/webmail_plugin_calendar/invites.py
@@ -193,7 +193,7 @@ def build_html(
         "</div>"
         '<p style="max-width:600px;margin:16px auto;color:#9aa0a6;font-size:12px;padding:0 4px">'
         "You are receiving this message because you are a guest of this event. "
-        "Sent by Webmail Calendar.</p>"
+        "Sent by Ultimo Calendar.</p>"
         "</body></html>"
     )
 
diff --git a/plugins/webmail_plugin_calendar/webmail_plugin_calendar/router.py b/plugins/webmail_plugin_calendar/webmail_plugin_calendar/router.py
index 121988e..8116be9 100644
--- a/plugins/webmail_plugin_calendar/webmail_plugin_calendar/router.py
+++ b/plugins/webmail_plugin_calendar/webmail_plugin_calendar/router.py
@@ -10,10 +10,14 @@ from __future__ import annotations
 
 import json
 import logging
+import re
 import secrets
 import uuid
 from datetime import UTC, datetime, timedelta
+from html import escape as html_escape
 from pathlib import Path
+from typing import Any
+from zoneinfo import ZoneInfo, ZoneInfoNotFoundError
 
 from fastapi import APIRouter, Depends, HTTPException, Query
 from fastapi.responses import FileResponse, HTMLResponse, Response
@@ -22,7 +26,7 @@ from sqlalchemy.exc import IntegrityError
 from sqlalchemy.ext.asyncio import AsyncSession
 
 from app.plugins.sdk import CurrentUserId, require_csrf, sdk
-from webmail_plugin_calendar import invites
+from webmail_plugin_calendar import imip, invites
 from webmail_plugin_calendar.queries import expand_range
 from webmail_plugin_calendar.schemas import (
     CalendarIn,
@@ -31,6 +35,7 @@ from webmail_plugin_calendar.schemas import (
     EditFollowingIn,
     EventIn,
     EventPatch,
+    InvitationAnswer,
     SubscribeIn,
 )
 
@@ -473,7 +478,15 @@ async def list_events(
     """List events overlapping [start, end). With ``q`` set, only events whose
     summary/location/description match (case-insensitive) are returned — used by
     the calendar search panel over a wide date window."""
-    range_start, range_end = _aware(start), _aware(end)
+    async with _SDK.session(user_id) as s:
+        return {"events": await _events_between(s, _aware(start), _aware(end), q)}
+
+
+async def _events_between(
+    s: AsyncSession, range_start: datetime, range_end: datetime, q: str = ""
+) -> list[dict[str, object]]:
+    """Every event occurrence overlapping [range_start, range_end), recurrence
+    expanded (the calendar views, search, and an invitation's conflicts)."""
     params: dict[str, object] = {"end": range_end}
     where = "WHERE e.dtstart < :end AND e.dav_deleted = false"
     term = q.strip()
@@ -483,23 +496,22 @@ async def list_events(
             "OR COALESCE(e.description, '') ILIKE :q)"
         )
         params["q"] = f"%{term}%"
-    async with _SDK.session(user_id) as s:
-        rows = (
-            await s.execute(
-                text(
-                    "SELECT e.id, e.calendar_id, e.ical_uid, e.summary, e.description, "
-                    "e.location, e.dtstart, e.dtend, e.all_day, e.tz, e.rrule, e.reminders, "
-                    "e.exdates, e.recurrence_id, e.status, "
-                    "e.my_partstat, e.origin_message_id, e.show_as, e.conference_url, "
-                    "e.attendees, e.organizer, "
-                    "COALESCE(e.color, c.color) AS color "
-                    "FROM plg_calendar_events e "
-                    "JOIN plg_calendar_calendars c ON c.id = e.calendar_id "
-                    f"{where}"
-                ),
-                params,
-            )
-        ).mappings().all()
+    rows = (
+        await s.execute(
+            text(
+                "SELECT e.id, e.calendar_id, e.ical_uid, e.summary, e.description, "
+                "e.location, e.dtstart, e.dtend, e.all_day, e.tz, e.rrule, e.reminders, "
+                "e.exdates, e.recurrence_id, e.status, "
+                "e.my_partstat, e.origin_message_id, e.show_as, e.conference_url, "
+                "e.attendees, e.organizer, "
+                "COALESCE(e.color, c.color) AS color "
+                "FROM plg_calendar_events e "
+                "JOIN plg_calendar_calendars c ON c.id = e.calendar_id "
+                f"{where}"
+            ),
+            params,
+        )
+    ).mappings().all()
     base = [
         r
         for r in rows
@@ -507,7 +519,7 @@ async def list_events(
         and (r["rrule"] is not None or (r["dtend"] or r["dtstart"]) > range_start)
     ]
     overrides = [r for r in rows if r["recurrence_id"] is not None]
-    return {"events": expand_range(base, overrides, range_start, range_end)}
+    return expand_range(base, overrides, range_start, range_end)
 
 
 async def _insert_event(
@@ -882,15 +894,32 @@ async def public_calendar(token: str) -> Response:
 
 # --- RSVP (public: guests respond from the invitation email, no login) --------
 
+def _logo_svg() -> str:
+    """The Ultimo signet, inline (a guest's browser loads nothing else), 56 px wide."""
+    try:
+        svg = (_UI / "ultimo-logo-signet.svg").read_text(encoding="utf-8")
+    except OSError:  # never let a missing picture stop the calendar from loading
+        return ""
+    svg = re.sub(r"<\?xml[^>]*\?>|<!--.*?-->", "", svg, flags=re.S).strip()
+    # Inkscape sizes it in mm: let the box decide (the viewBox keeps its shape).
+    return re.sub(r"<svg\b([^>]*?)\swidth=\"[^\"]*\"([^>]*?)\sheight=\"[^\"]*\"",
+                  r'<svg\1 width="56"\2 height="54"', svg, count=1)
+
+
+_LOGO = _logo_svg()
+
+
 def _rsvp_page(message: str) -> str:
+    """What a guest sees after clicking Yes / No / Maybe in our invitation."""
     return (
         "<!doctype html><html><head><meta charset='utf-8'>"
         "<meta name='viewport' content='width=device-width, initial-scale=1'>"
-        "<title>Invitation response</title></head>"
+        "<title>Invitation response · Ultimo Calendar</title></head>"
         "<body style='margin:0;font-family:Arial,Helvetica,sans-serif;background:#f1f3f4;"
         "color:#3c4043'><div style='max-width:460px;margin:64px auto;background:#fff;"
         "border:1px solid #e0e0e0;border-radius:8px;padding:32px;text-align:center'>"
-        "<h2 style='margin:0 0 12px;font-size:18px'>Webmail Calendar</h2>"
+        f"<div style='display:flex;justify-content:center;margin:0 0 14px'>{_LOGO}</div>"
+        "<h2 style='margin:0 0 12px;font-size:18px'>Ultimo Calendar</h2>"
         f"<p style='margin:0;color:#5f6368'>{message}</p></div></body></html>"
     )
 
@@ -929,11 +958,327 @@ async def rsvp(t: str = Query(...), r: str = Query(...)) -> HTMLResponse:
     return HTMLResponse(_rsvp_page(f"Your response “{invites.RESPONSES[r]}” was recorded."))
 
 
+# --- invitations received by email (iMIP) -----------------------------------
+#
+# The reading pane shows an invitation email as a card (core MessageInvitation):
+# when, what, where, who organizes, what else is in the calendar then, and
+# Yes / No / Maybe. Answering adds (or updates, or removes) the event in the
+# user's calendar and sends the organizer an iTIP REPLY, so their calendar
+# records the answer too.
+
+_ANSWERS = ("accepted", "declined", "tentative")
+
+
+def _declined_key(inv: dict[str, Any]) -> str:
+    """Where a "No" is remembered: declining takes the event out of the calendar,
+    so the calendar no longer holds the answer the card should show."""
+    rid = inv["recurrence_id"].isoformat() if inv["recurrence_id"] else ""
+    return f"declined:{inv['uid']}:{rid}"
+
+
+async def _invitation(user_id: uuid.UUID, message_id: uuid.UUID) -> tuple[str, dict[str, Any]]:
+    raw = await _SDK.messages.raw(user_id, message_id)
+    ics = imip.calendar_part(raw) if raw else None
+    inv = imip.parse_invite(ics) if ics else None
+    if ics is None or inv is None or not inv["uid"]:
+        raise HTTPException(status_code=404, detail="no_invitation")
+    return ics, inv
+
+
+async def _me(user_id: uuid.UUID, inv: dict[str, Any]) -> dict[str, str] | None:
+    """The user among the invitation's attendees (any of their accounts)."""
+    mine = {e.lower(): n for _a, e, n in await _SDK.accounts.of_user(user_id)}
+    for a in inv["attendees"]:
+        if a["email"] in mine:
+            name = a.get("name") or mine[a["email"]]
+            return {"email": a["email"], "name": name, "partstat": a["partstat"]}
+    return None
+
+
+async def _invited_copy(s: AsyncSession, inv: dict[str, Any]) -> dict[str, Any] | None:
+    """The event this invitation already put in the user's calendar, if any."""
+    row = (
+        await s.execute(
+            text(
+                "SELECT e.id, e.calendar_id, e.sequence, e.my_partstat, c.kind, c.name "
+                "FROM plg_calendar_events e JOIN plg_calendar_calendars c ON c.id = e.calendar_id "
+                "WHERE e.ical_uid = :uid AND e.recurrence_id IS NOT DISTINCT FROM :rid "
+                "AND e.dav_deleted = false ORDER BY e.sequence DESC LIMIT 1"
+            ),
+            {"uid": inv["uid"], "rid": inv["recurrence_id"]},
+        )
+    ).mappings().first()
+    return dict(row) if row else None
+
+
+async def _invitation_calendar(s: AsyncSession, user_id: uuid.UUID) -> uuid.UUID:
+    """Where accepted invitations go: Settings → Calendars → Invitations, else
+    the default calendar, else the first one that can be written to."""
+    settings = await _SDK.accounts.settings_of(user_id)
+    await _ensure_default_calendar(s, user_id)
+    rows = (
+        await s.execute(
+            text("SELECT id FROM plg_calendar_calendars WHERE read_only = false ORDER BY name")
+        )
+    ).scalars().all()
+    writable = [str(r) for r in rows]
+    for wanted in (settings.get("invitation_calendar"), settings.get("default_calendar")):
+        if wanted and str(wanted) in writable:
+            return uuid.UUID(str(wanted))
+    return uuid.UUID(writable[0])
+
+
+def _brief(ev: dict[str, Any]) -> dict[str, Any]:
+    return {k: ev.get(k) for k in ("summary", "start", "end", "all_day", "color")}
+
+
+async def _invitation_view(user_id: uuid.UUID, message_id: uuid.UUID) -> dict[str, Any]:
+    _ics, inv = await _invitation(user_id, message_id)
+    me = await _me(user_id, inv)
+    start, end = inv["dtstart"], inv["dtend"]
+    settings = await _SDK.accounts.settings_of(user_id)
+    try:
+        zone = ZoneInfo(str(settings.get("tz") or inv["tz"]))
+    except (ZoneInfoNotFoundError, ValueError):
+        zone = ZoneInfo("UTC")
+    day_start = start.astimezone(zone).replace(hour=0, minute=0, second=0, microsecond=0)
+    async with _SDK.session(user_id) as s:
+        copy = await _invited_copy(s, inv)
+        around = await _events_between(s, day_start, max(end, day_start + timedelta(days=1)))
+    others = [
+        e
+        for e in around
+        if e.get("ical_uid") != inv["uid"]
+        and e.get("status") != "cancelled"
+        and e.get("my_partstat") != "declined"
+    ]
+
+    def times(e: dict[str, Any]) -> tuple[datetime, datetime]:
+        return datetime.fromisoformat(str(e["start"])), datetime.fromisoformat(str(e["end"]))
+
+    # What the user is already busy with then (timed events, unless this one is
+    # all-day), and else the event just before it that day.
+    conflicts = [
+        _brief(e)
+        for e in others
+        if e.get("show_as") != "free"
+        and (inv["all_day"] or not e.get("all_day"))
+        and times(e)[0] < end
+        and times(e)[1] > start
+    ]
+    earlier = sorted(
+        (e for e in others if not e.get("all_day") and times(e)[1] <= start),
+        key=lambda e: times(e)[1],
+    )
+    declined = await _SDK.kv(user_id).get(_declined_key(inv))
+    response = (
+        (copy or {}).get("my_partstat")
+        or ("declined" if declined else None)
+        or (me or {}).get("partstat")
+        or "needs-action"
+    )
+    return {
+        "method": inv["method"],
+        "uid": inv["uid"],
+        "summary": inv["summary"],
+        "description": inv["description"],
+        "location": inv["location"],
+        "conference_url": inv["conference_url"],
+        "start": start.isoformat(),
+        "end": end.isoformat(),
+        "all_day": inv["all_day"],
+        "tz": inv["tz"],
+        "recurring": inv["rrule"] is not None,
+        "status": inv["status"],
+        "organizer": inv["organizer"],
+        "attendees": inv["attendees"],
+        "me": {"email": me["email"], "name": me["name"]} if me else None,
+        "response": response,
+        "in_calendar": (
+            {"event_id": str(copy["id"]), "calendar": copy["name"]} if copy else None
+        ),
+        # The calendar holds a newer version (the organizer changed it since).
+        "outdated": bool(copy and int(copy["sequence"]) > inv["sequence"]),
+        "conflicts": conflicts,
+        "previous": _brief(earlier[-1]) if earlier and not conflicts else None,
+    }
+
+
+@router.get("/invitations/{message_id}")
+async def get_invitation(message_id: uuid.UUID, user_id: CurrentUserId) -> dict[str, Any]:
+    """The invitation in an email, as the reading pane shows it; 404 if none."""
+    return await _invitation_view(user_id, message_id)
+
+
+def _default_reminders(settings: dict[str, Any]) -> list[int]:
+    out = []
+    for r in settings.get("default_reminders_timed") or []:
+        minutes = r.get("minutes") if isinstance(r, dict) else r
+        if isinstance(minutes, int):
+            out.append(minutes)
+    return out
+
+
+@router.post("/invitations/{message_id}/respond", dependencies=[Depends(require_csrf)])
+async def respond_to_invitation(
+    message_id: uuid.UUID, body: InvitationAnswer, user_id: CurrentUserId
+) -> dict[str, Any]:
+    """Answer an invitation: Yes / Maybe put it in the calendar (or update it),
+    No takes it out; then the organizer gets the iTIP REPLY."""
+    if body.response not in _ANSWERS:
+        raise HTTPException(status_code=400, detail="bad_response")
+    ics, inv = await _invitation(user_id, message_id)
+    if inv["method"] != "REQUEST":
+        raise HTTPException(status_code=400, detail="not_a_request")
+    me = await _me(user_id, inv)
+    if me is None:
+        raise HTTPException(status_code=400, detail="not_invited")
+    attendees = [
+        {**a, "partstat": body.response} if a["email"] == me["email"] else a
+        for a in inv["attendees"]
+    ]
+    dav_calendar: str | None = None
+    async with _SDK.session(user_id) as s:
+        copy = await _invited_copy(s, inv)
+        if body.response == "declined":
+            if copy is not None:
+                await s.execute(
+                    text(
+                        "UPDATE plg_calendar_events SET dav_deleted = true WHERE id = :id"
+                        if copy["kind"] == "caldav"
+                        else "DELETE FROM plg_calendar_events WHERE id = :id"
+                    ),
+                    {"id": str(copy["id"])},
+                )
+                dav_calendar = str(copy["calendar_id"]) if copy["kind"] == "caldav" else None
+        elif copy is not None and int(copy["sequence"]) > inv["sequence"]:
+            # An older copy of the invitation: keep the newer event, just answer.
+            await s.execute(
+                text("UPDATE plg_calendar_events SET my_partstat = :p WHERE id = :id"),
+                {"p": body.response, "id": str(copy["id"])},
+            )
+            dav_calendar = str(copy["calendar_id"]) if copy["kind"] == "caldav" else None
+        else:
+            fields = {
+                "sum": inv["summary"],
+                "desc": inv["description"],
+                "loc": inv["location"],
+                "start": inv["dtstart"],
+                "end": inv["dtend"],
+                "allday": inv["all_day"],
+                "tz": inv["tz"],
+                "rrule": inv["rrule"],
+                "rid": inv["recurrence_id"],
+                "status": "cancelled" if inv["status"] == "cancelled" else "confirmed",
+                "org": json.dumps(inv["organizer"]) if inv["organizer"] else None,
+                "att": json.dumps(attendees),
+                "mine": body.response,
+                "seq": inv["sequence"],
+                "raw": ics,
+                "msg": str(message_id),
+                "conf": inv["conference_url"],
+                "showas": inv["show_as"],
+            }
+            if copy is not None:
+                await s.execute(
+                    text(
+                        "UPDATE plg_calendar_events SET summary = :sum, description = :desc, "
+                        "location = :loc, dtstart = :start, dtend = :end, all_day = :allday, "
+                        "tz = :tz, rrule = :rrule, status = :status, "
+                        "organizer = CAST(:org AS jsonb), attendees = CAST(:att AS jsonb), "
+                        "my_partstat = :mine, sequence = :seq, raw_ical = :raw, "
+                        "origin_message_id = :msg, conference_url = :conf, show_as = :showas "
+                        "WHERE id = :id"
+                    ),
+                    {**fields, "id": str(copy["id"])},
+                )
+                dav_calendar = str(copy["calendar_id"]) if copy["kind"] == "caldav" else None
+            else:
+                calendar_id = await _invitation_calendar(s, user_id)
+                settings = await _SDK.accounts.settings_of(user_id)
+                await s.execute(
+                    text(
+                        "INSERT INTO plg_calendar_events "
+                        "(user_id, calendar_id, ical_uid, summary, description, location, "
+                        " dtstart, dtend, all_day, tz, rrule, recurrence_id, status, organizer, "
+                        " attendees, my_partstat, sequence, raw_ical, origin_message_id, "
+                        " conference_url, show_as, reminders) "
+                        "VALUES (:u, :cal, :uid, :sum, :desc, :loc, :start, :end, :allday, :tz, "
+                        " :rrule, :rid, :status, CAST(:org AS jsonb), CAST(:att AS jsonb), :mine, "
+                        " :seq, :raw, :msg, :conf, :showas, :rem)"
+                    ),
+                    {
+                        **fields,
+                        "u": str(user_id),
+                        "cal": str(calendar_id),
+                        "uid": inv["uid"],
+                        "rem": _default_reminders(settings),
+                    },
+                )
+                if await _is_caldav(s, calendar_id):
+                    dav_calendar = str(calendar_id)
+    if dav_calendar:
+        await _enqueue_dav_sync(uuid.UUID(dav_calendar))
+    kv = _SDK.kv(user_id)
+    if body.response == "declined":
+        await kv.set(_declined_key(inv), True)
+    else:
+        await kv.delete(_declined_key(inv))
+
+    # Tell the organizer — unless the user organized it themselves.
+    organizer = inv["organizer"]
+    reply_sent = False
+    if organizer and organizer["email"] != me["email"]:
+        who = me["name"] or me["email"]
+        word = {"accepted": "accepted", "declined": "declined", "tentative": "tentatively accepted"}
+        sentence = f"{who} has {word[body.response]} this invitation."
+        try:
+            await _SDK.mail.send(
+                user_id,
+                to=[organizer["email"]],
+                subject=imip.reply_subject(body.response, inv["summary"]),
+                html=f"<p>{html_escape(sentence)}</p>",
+                text=sentence,
+                from_email=me["email"],
+                ics=imip.build_reply(ics, me, body.response),
+                ics_method="REPLY",
+                ics_filename="reply.ics",
+            )
+            reply_sent = True
+        except Exception:  # noqa: BLE001 - the calendar is updated either way
+            _log.exception("invitation reply to %s failed", organizer["email"])
+    view = await _invitation_view(user_id, message_id)
+    view["reply_sent"] = reply_sent
+    return view
+
+
+@router.post("/invitations/{message_id}/remove", dependencies=[Depends(require_csrf)])
+async def remove_cancelled_event(message_id: uuid.UUID, user_id: CurrentUserId) -> dict[str, Any]:
+    """The organizer cancelled the event: take it out of the calendar."""
+    _ics, inv = await _invitation(user_id, message_id)
+    dav_calendar: str | None = None
+    async with _SDK.session(user_id) as s:
+        copy = await _invited_copy(s, inv)
+        if copy is not None:
+            await s.execute(
+                text(
+                    "UPDATE plg_calendar_events SET dav_deleted = true WHERE id = :id"
+                    if copy["kind"] == "caldav"
+                    else "DELETE FROM plg_calendar_events WHERE id = :id"
+                ),
+                {"id": str(copy["id"])},
+            )
+            dav_calendar = str(copy["calendar_id"]) if copy["kind"] == "caldav" else None
+    if dav_calendar:
+        await _enqueue_dav_sync(uuid.UUID(dav_calendar))
+    return await _invitation_view(user_id, message_id)
+
+
 # --- bundle ------------------------------------------------------------------
 
 @router.get("/ui/{filename}")
 async def bundle(filename: str) -> FileResponse:
-    if filename != "page.js":
+    if filename not in ("page.js", "invite.js"):
         raise HTTPException(status_code=404)
     # `no-cache` = the browser must revalidate before reusing (ETag makes a 304 cheap),
     # so an edited bundle is picked up on the next page reload instead of a stale copy.
diff --git a/plugins/webmail_plugin_calendar/webmail_plugin_calendar/schemas.py b/plugins/webmail_plugin_calendar/webmail_plugin_calendar/schemas.py
index 4869736..640fc03 100644
--- a/plugins/webmail_plugin_calendar/webmail_plugin_calendar/schemas.py
+++ b/plugins/webmail_plugin_calendar/webmail_plugin_calendar/schemas.py
@@ -78,3 +78,9 @@ class EventPatch(BaseModel):
     color: str | None = None
     show_as: str | None = None
     conference_url: str | None = None
+
+
+class InvitationAnswer(BaseModel):
+    """Yes / No / Maybe to an emailed invitation (iTIP PARTSTAT)."""
+
+    response: str  # accepted | declined | tentative
diff --git a/plugins/webmail_plugin_calendar/webmail_plugin_calendar/ui/invite.js b/plugins/webmail_plugin_calendar/webmail_plugin_calendar/ui/invite.js
new file mode 100644
index 0000000..f4f3d54
--- /dev/null
+++ b/plugins/webmail_plugin_calendar/webmail_plugin_calendar/ui/invite.js
@@ -0,0 +1,244 @@
+// calendar · message.banner slot: an invitation received by email (iMIP).
+//
+// Above the message body: when, what, where, who organizes, what else is in the
+// calendar then, and Yes / No / Maybe. Answering puts the event in the calendar
+// (or takes it out) and sends the organizer the reply their calendar reads.
+//
+// Mounts on every opened message, so it stays silent and cheap for ordinary
+// mail: nothing without attachments, and only a message with an .ics attachment
+// asks the server about an invitation.
+
+const STYLE_ID = "cal-invite-styles";
+const CSS = `
+.cal-inv { margin: 4px 16px 12px; padding: 16px 18px; border: 1px solid rgb(var(--app-border));
+  border-radius: 10px; background: rgb(var(--app-surface)); color: rgb(var(--app-fg)); font-size: 14px; }
+.cal-inv-when { font-weight: 600; font-size: 13px; }
+.cal-inv-when .cal-inv-sep { margin: 0 6px; opacity: .6; }
+.cal-inv-title { margin: 4px 0 14px; font-size: 21px; line-height: 1.25; word-break: break-word; }
+.cal-inv-cancelled .cal-inv-title { text-decoration: line-through; opacity: .7; }
+.cal-inv-grid { display: grid; grid-template-columns: repeat(auto-fit, minmax(220px, 1fr)); gap: 10px 24px; }
+.cal-inv-row { display: flex; align-items: flex-start; gap: 12px; min-width: 0; color: rgb(var(--app-fg)); }
+.cal-inv-row svg { flex: none; margin-top: 1px; color: rgb(var(--app-muted)); }
+.cal-inv-row .cal-inv-text { min-width: 0; overflow-wrap: anywhere; }
+.cal-inv-row a { color: rgb(var(--app-accent)); text-decoration: none; }
+.cal-inv-row a:hover { text-decoration: underline; }
+.cal-inv-faint { color: rgb(var(--app-muted)); }
+.cal-inv-cal { margin-top: 12px; }
+.cal-inv-label { font-size: 11px; font-weight: 700; text-transform: uppercase; letter-spacing: .03em;
+  color: rgb(var(--app-muted)); margin-bottom: 2px; }
+.cal-inv-conflict { color: rgb(217 119 6); }
+.cal-inv-btns { display: flex; flex-wrap: wrap; align-items: center; gap: 8px; margin-top: 16px; }
+.cal-inv-btn { min-width: 72px; padding: 8px 18px; border-radius: 999px; font-weight: 600; font-size: 14px;
+  border: 1px solid rgb(var(--app-border)); background: rgb(var(--app-hover)); color: rgb(var(--app-fg));
+  cursor: pointer; }
+.cal-inv-btn:hover:not(:disabled) { border-color: rgb(var(--app-accent)); }
+.cal-inv-btn.on { background: rgb(var(--app-accent)); border-color: rgb(var(--app-accent));
+  color: rgb(var(--app-accent-fg)); }
+.cal-inv-btn:disabled { opacity: .6; cursor: default; }
+.cal-inv-note { font-size: 12px; color: rgb(var(--app-muted)); }
+.cal-inv-note.err { color: rgb(220 38 38); }
+.cal-inv-badge { display: inline-block; margin-left: 8px; padding: 1px 7px; border-radius: 6px; font-size: 11px;
+  font-weight: 700; text-transform: uppercase; vertical-align: 2px; background: rgb(220 38 38 / .15); color: rgb(220 38 38); }
+`;
+
+const ICON = {
+  place:
+    '<svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.7" stroke-linecap="round" stroke-linejoin="round"><path d="M12 21s-7-6.2-7-11.5a7 7 0 0 1 14 0C19 14.8 12 21 12 21z"/><circle cx="12" cy="9.5" r="2.5"/></svg>',
+  video:
+    '<svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.7" stroke-linecap="round" stroke-linejoin="round"><rect x="3" y="6" width="13" height="12" rx="2"/><path d="M16 10.5l5-3v9l-5-3z"/></svg>',
+  people:
+    '<svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.7" stroke-linecap="round" stroke-linejoin="round"><circle cx="9" cy="8" r="3.2"/><path d="M3 19c.6-3.3 3-5 6-5s5.4 1.7 6 5"/><circle cx="17" cy="9" r="2.4"/><path d="M15.5 14.2c2.6-.3 4.7 1.2 5.5 4.3"/></svg>',
+  calendar:
+    '<svg width="18" height="18" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.7" stroke-linecap="round" stroke-linejoin="round"><rect x="3.5" y="5" width="17" height="15.5" rx="2"/><path d="M3.5 10h17M8 3v4M16 3v4"/></svg>',
+};
+
+function esc(s) {
+  return String(s ?? "").replace(/[&<>"]/g, (c) => ({ "&": "&amp;", "<": "&lt;", ">": "&gt;", '"': "&quot;" })[c]);
+}
+
+// 12/24-hour and date order follow Settings → Appearance, like the rest of Mail.
+let hour12Promise = null;
+function hour12(ctx) {
+  hour12Promise ??= ctx.api
+    .fetch("/settings")
+    .then((s) => s && s.time_format === "12")
+    .catch(() => false);
+  return hour12Promise;
+}
+
+function clock(d, h12) {
+  return d.toLocaleTimeString(h12 ? "en-US" : "en-GB", { hour: h12 ? "numeric" : "2-digit", minute: "2-digit", hour12: h12 });
+}
+
+function dayLabel(d, h12) {
+  const today = new Date();
+  const tomorrow = new Date(today);
+  tomorrow.setDate(today.getDate() + 1);
+  if (d.toDateString() === today.toDateString()) return "Today";
+  if (d.toDateString() === tomorrow.toDateString()) return "Tomorrow";
+  const sameYear = d.getFullYear() === today.getFullYear();
+  return d.toLocaleDateString(h12 ? "en-US" : "en-GB", {
+    weekday: "short",
+    day: "numeric",
+    month: "short",
+    ...(sameYear ? {} : { year: "numeric" }),
+  });
+}
+
+function whenLine(inv, h12) {
+  const s = new Date(inv.start);
+  const e = new Date(inv.end);
+  const sep = '<span class="cal-inv-sep">•</span>';
+  if (inv.all_day) {
+    // An all-day event ends at the start of the day after its last one.
+    const last = new Date(e.getTime() - 1);
+    const days = last.toDateString() === s.toDateString() ? dayLabel(s, h12) : `${dayLabel(s, h12)} – ${dayLabel(last, h12)}`;
+    return `${esc(days)}${sep}All day`;
+  }
+  const sameDay = s.toDateString() === e.toDateString();
+  const range = sameDay
+    ? `${clock(s, h12)} – ${clock(e, h12)}`
+    : `${clock(s, h12)} – ${esc(dayLabel(e, h12))} ${clock(e, h12)}`;
+  return `${esc(dayLabel(s, h12))}${sep}${range}${inv.recurring ? `${sep}Repeats` : ""}`;
+}
+
+function eventSpan(ev, h12) {
+  if (ev.all_day) return "all day";
+  return `${clock(new Date(ev.start), h12)} – ${clock(new Date(ev.end), h12)}`;
+}
+
+function calendarLine(inv, h12) {
+  if (inv.conflicts && inv.conflicts.length) {
+    const first = inv.conflicts[0];
+    const more = inv.conflicts.length > 1 ? ` and ${inv.conflicts.length - 1} more` : "";
+    return `<span class="cal-inv-conflict">Conflicts with: ${esc(first.summary || "(no title)")} at ${eventSpan(first, h12)}${more}</span>`;
+  }
+  if (inv.previous) {
+    return `Previous event: ${esc(inv.previous.summary || "(no title)")} at ${eventSpan(inv.previous, h12)}`;
+  }
+  return '<span class="cal-inv-faint">No other events at that time</span>';
+}
+
+const ANSWERS = [
+  ["accepted", "Yes"],
+  ["declined", "No"],
+  ["tentative", "Maybe"],
+];
+
+function render(el, inv, h12, note) {
+  const cancelled = inv.method === "CANCEL" || inv.status === "cancelled";
+  const org = inv.organizer;
+  const orgLabel = org ? `${esc(org.name || org.email)} <span class="cal-inv-faint">– organizer</span>` : "";
+  const conf = inv.conference_url;
+  // A meeting link given as the location reads better as a link.
+  const place =
+    conf && (!inv.location || inv.location === conf)
+      ? `<div class="cal-inv-row">${ICON.video}<span class="cal-inv-text"><a href="${esc(conf)}" target="_blank" rel="noopener noreferrer">Join video call</a></span></div>`
+      : inv.location
+        ? `<div class="cal-inv-row">${ICON.place}<span class="cal-inv-text">${esc(inv.location)}${
+            conf ? ` · <a href="${esc(conf)}" target="_blank" rel="noopener noreferrer">Join video call</a>` : ""
+          }</span></div>`
+        : "";
+  let actions = "";
+  if (cancelled) {
+    actions = inv.in_calendar
+      ? '<div class="cal-inv-btns"><button class="cal-inv-btn" data-remove>Remove from calendar</button></div>'
+      : '<div class="cal-inv-btns"><span class="cal-inv-note">Not in your calendar.</span></div>';
+  } else if (inv.method === "REQUEST" && inv.me) {
+    actions =
+      '<div class="cal-inv-btns">' +
+      ANSWERS.map(
+        ([value, label]) =>
+          `<button class="cal-inv-btn${inv.response === value ? " on" : ""}" data-answer="${value}" aria-pressed="${inv.response === value}">${label}</button>`,
+      ).join("") +
+      (note ? `<span class="cal-inv-note${note.err ? " err" : ""}">${esc(note.text)}</span>` : "") +
+      "</div>";
+  } else if (inv.method === "REQUEST") {
+    actions = '<div class="cal-inv-btns"><span class="cal-inv-note">You are not on the guest list of this event.</span></div>';
+  }
+  el.innerHTML = `
+    <div class="cal-inv${cancelled ? " cal-inv-cancelled" : ""}" role="group" aria-label="Event invitation">
+      <div class="cal-inv-when">${whenLine(inv, h12)}${cancelled ? '<span class="cal-inv-badge">Cancelled</span>' : ""}</div>
+      <div class="cal-inv-title">${esc(inv.summary || "(no title)")}</div>
+      <div class="cal-inv-grid">
+        ${place}
+        ${org ? `<div class="cal-inv-row">${ICON.people}<span class="cal-inv-text">${orgLabel}</span></div>` : ""}
+      </div>
+      ${
+        cancelled
+          ? ""
+          : `<div class="cal-inv-row cal-inv-cal">${ICON.calendar}<span class="cal-inv-text">
+              <div class="cal-inv-label">In calendar${inv.in_calendar ? ` · ${esc(inv.in_calendar.calendar)}` : ""}</div>
+              ${calendarLine(inv, h12)}
+              ${inv.outdated ? '<div class="cal-inv-faint">Your calendar has a newer version of this event.</div>' : ""}
+            </span></div>`
+      }
+      ${actions}
+    </div>`;
+}
+
+export default function mount(el, ctx, props) {
+  const messageId = props && props.messageId;
+  // Ordinary mail stays silent: invitations come with an .ics attached.
+  if (!messageId || props.hasAttachments === false) return;
+  let disposed = false;
+  if (!document.getElementById(STYLE_ID)) {
+    const style = document.createElement("style");
+    style.id = STYLE_ID;
+    style.textContent = CSS;
+    document.head.appendChild(style);
+  }
+
+  async function show(inv, note) {
+    const h12 = await hour12(ctx);
+    if (disposed) return;
+    render(el, inv, h12, note);
+    el.querySelectorAll("[data-answer]").forEach((b) =>
+      b.addEventListener("click", () => answer(b.dataset.answer, inv)),
+    );
+    const remove = el.querySelector("[data-remove]");
+    if (remove) remove.addEventListener("click", () => send(`/invitations/${messageId}/remove`, {}, inv, "Removed from your calendar."));
+  }
+
+  async function send(path, body, inv, okText) {
+    el.querySelectorAll("button").forEach((b) => (b.disabled = true));
+    try {
+      const next = await ctx.api.pluginFetch(path, { method: "POST", body: JSON.stringify(body) });
+      window.dispatchEvent(new CustomEvent("webmail:calendar-changed"));
+      await show(next, { text: typeof okText === "function" ? okText(next) : okText });
+    } catch {
+      await show(inv, { text: "Couldn't save your answer. Try again.", err: true });
+    }
+  }
+
+  function answer(value, inv) {
+    send(`/invitations/${messageId}/respond`, { response: value }, inv, (next) => {
+      // The reply going out is the toast's news (Mail's corner toast, like Undo).
+      if (next.reply_sent) {
+        window.dispatchEvent(new CustomEvent("webmail:toast", { detail: { text: "Reply sent" } }));
+      }
+      return value === "declined"
+        ? "Not in your calendar."
+        : `Saved in ${next.in_calendar ? next.in_calendar.calendar : "your calendar"}.`;
+    });
+  }
+
+  (async () => {
+    try {
+      const files = await ctx.api.fetch(`/messages/${messageId}/attachments`);
+      const hasIcs = (files || []).some(
+        (a) => /\.ics$/i.test(a.filename || "") || /calendar|ics/i.test(a.mime_type || ""),
+      );
+      if (!hasIcs || disposed) return;
+      const inv = await ctx.api.pluginFetch(`/invitations/${messageId}`);
+      if (!disposed && inv) await show(inv, null);
+    } catch {
+      /* not an invitation (404), or offline: no banner — never block the message */
+    }
+  })();
+
+  return () => {
+    disposed = true;
+    el.innerHTML = "";
+  };
+}
diff --git a/plugins/webmail_plugin_calendar/webmail_plugin_calendar/ui/page.js b/plugins/webmail_plugin_calendar/webmail_plugin_calendar/ui/page.js
index be01ead..c7dd210 100644
--- a/plugins/webmail_plugin_calendar/webmail_plugin_calendar/ui/page.js
+++ b/plugins/webmail_plugin_calendar/webmail_plugin_calendar/ui/page.js
@@ -132,7 +132,10 @@ const videoLinkHtml = (link) => `<div class="cal-videolink">
   <svg width="15" height="15" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.8" stroke-linecap="round" stroke-linejoin="round"><path d="M23 7l-7 5 7 5V7z"/><rect x="1" y="5" width="15" height="14" rx="2"/></svg>
   <a href="${esc(link)}" target="_blank" rel="noopener noreferrer">${esc(link)}</a>
   <button class="cal-iconbtn" type="button" data-act="copy-jitsi" title="Copy link"><svg width="15" height="15" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.7" stroke-linecap="round" stroke-linejoin="round"><rect x="9" y="9" width="13" height="13" rx="2"/><path d="M5 15H4a2 2 0 0 1-2-2V4a2 2 0 0 1 2-2h9a2 2 0 0 1 2 2v1"/></svg></button>
+  <button class="cal-iconbtn" type="button" data-act="remove-video" title="Remove video call" aria-label="Remove video call"><svg width="15" height="15" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.9" stroke-linecap="round"><path d="M6 6l12 12M18 6L6 18"/></svg></button>
 </div>`;
+// The Video-call section without a link: the button that adds one.
+const ADD_VIDEO_HTML = `<button class="cal-btn" data-act="add-jitsi" style="display:inline-flex;align-items:center;gap:6px"><svg width="15" height="15" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.8" stroke-linecap="round" stroke-linejoin="round" style="flex:0 0 auto"><path d="M23 7l-7 5 7 5V7z"/><rect x="1" y="5" width="15" height="14" rx="2"/></svg>Add a video call in Jitsi Meet</button>`;
 
 const COLORS = [
   ["Blue", "#3b82f6"], ["Green", "#22c55e"], ["Red", "#ef4444"], ["Orange", "#f97316"],
@@ -335,6 +338,9 @@ const CSS = `
 .cal-agenda .day .dt{width:44px;flex:0 0 auto;font-size:12px;color:rgb(var(--app-muted))}
 .cal-agenda .day .dt b{display:block;font-size:18px;color:rgb(var(--app-fg))}
 .cal-agenda .none{color:rgb(var(--app-faint));font-size:13px}
+.cal-agenda .day.empty{cursor:pointer}
+.cal-agenda .day.empty:hover{background:rgb(var(--app-hover))}
+.cal-agenda .day.empty:hover .none{color:rgb(var(--app-accent))}
 /* new-event form (floating box) */
 /* Content-sized box: grows in height as sections are added, scrolls only past the
    viewport cap; the Save/Cancel footer sticks to the bottom while scrolling. */
@@ -935,6 +941,19 @@ export default function mount(el, ctx, props) {
     box.innerHTML = videoLinkHtml(link);
     const copyBtn = box.querySelector("[data-act=copy-jitsi]");
     if (copyBtn) copyBtn.addEventListener("click", () => copyLink(link, copyBtn));
+    const removeBtn = box.querySelector("[data-act=remove-video]");
+    if (removeBtn) removeBtn.addEventListener("click", clearVideo);
+  }
+  // ✕ on the link: no video call — and none re-added when another guest is invited.
+  function clearVideo() {
+    if (!state.composing) return;
+    state.composing.conference = "";
+    state.composing.videoRemoved = true;
+    const box = el.querySelector("[data-video]");
+    if (!box) return;
+    box.innerHTML = ADD_VIDEO_HTML;
+    const add = box.querySelector("[data-act=add-jitsi]");
+    if (add) add.addEventListener("click", () => fillVideo(jitsiLink(state.jitsi)));
   }
   function copyLink(link, btn) {
     try { navigator.clipboard.writeText(link); } catch { /* ignore */ }
@@ -968,7 +987,9 @@ export default function mount(el, ctx, props) {
         guests.appendChild(span);
         // Adding a NEW guest auto-provisions a video call if none exists yet
         // (skipped when restoring an existing event's guests during edit).
-        if (autoVideo && !state.composing.conference) fillVideo(jitsiLink(state.jitsi));
+        if (autoVideo && !state.composing.conference && !state.composing.videoRemoved) {
+          fillVideo(jitsiLink(state.jitsi));
+        }
       }
       inp.value = "";
       acpop.style.display = "none";
@@ -1296,7 +1317,7 @@ export default function mount(el, ctx, props) {
         <h4>Video call</h4>
         <div data-video>${c.conference
           ? videoLinkHtml(c.conference)
-          : `<button class="cal-btn" data-act="add-jitsi" style="display:inline-flex;align-items:center;gap:6px"><svg width="15" height="15" viewBox="0 0 24 24" fill="none" stroke="currentColor" stroke-width="1.8" stroke-linecap="round" stroke-linejoin="round" style="flex:0 0 auto"><path d="M23 7l-7 5 7 5V7z"/><rect x="1" y="5" width="15" height="14" rx="2"/></svg>Add a video call in Jitsi Meet</button>`}</div>
+          : ADD_VIDEO_HTML}</div>
         <h4>Reminders</h4>
         <div data-reminders></div>
         <button class="cal-btn" data-act="add-reminder" style="margin-top:6px">＋ Add reminder</button>
@@ -1482,7 +1503,10 @@ export default function mount(el, ctx, props) {
       const d = addDays(start, i);
       if (!short && d.getMonth() !== start.getMonth()) break;
       const dayEvs = evs.filter((ev) => sameDay(ev._s, d)).sort((a, b) => a._s - b._s);
-      html += `<div class="day" data-agday="${d.getFullYear()}-${pad2(d.getMonth() + 1)}-${pad2(d.getDate())}"><div class="dt">${DAYNAMES[(d.getDay() + 6) % 7].toUpperCase()}<b>${d.getDate()}</b></div><div style="flex:1">${
+      const key = `${d.getFullYear()}-${pad2(d.getMonth() + 1)}-${pad2(d.getDate())}`;
+      // An empty day is a place to add one: click → new event on that date.
+      const empty = dayEvs.length ? "" : ` empty" data-newday="${key}" role="button" title="New event on this day`;
+      html += `<div class="day${empty}" data-agday="${key}"><div class="dt">${DAYNAMES[(d.getDay() + 6) % 7].toUpperCase()}<b>${d.getDate()}</b></div><div style="flex:1">${
         dayEvs.length ? dayEvs.map((ev) => `<div class="cal-ev" data-ev="${ev.id}" data-start="${esc(ev.start)}" style="border-color:${esc(ev.color)}">${ev.all_day ? "" : hhmm(ev._s) + " "}${esc(ev.summary || "(no title)")}</div>`).join("") : `<span class="none">No events</span>`
       }</div></div>`;
     }
@@ -1540,6 +1564,12 @@ export default function mount(el, ctx, props) {
     act("add-calendar", () => ctx.navigate("/settings/calendars?from=%2Fp%2Fcalendar&create=1"));
     act("signout", async () => { await api.fetch("/auth/logout", { method: "POST" }); ctx.navigate("/login"); });
     act("new", () => openForm(null));
+    on("[data-newday]", "click", (e) => {
+      // That day, at the current time of day (as clicking a day in Month view).
+      const [y, m, dd] = e.currentTarget.dataset.newday.split("-").map(Number);
+      const now = new Date();
+      openForm(new Date(y, m - 1, dd, now.getHours(), now.getMinutes()));
+    });
     act("today", () => { state.anchor = startOfDay(new Date()); state.mini = startOfMonth(state.anchor); reload(); });
     act("prev", () => go(-1));
     act("next", () => go(1));
@@ -1710,6 +1740,7 @@ export default function mount(el, ctx, props) {
     act("add-jitsi", () => fillVideo(jitsiLink(state.jitsi)));
     // Copy handler for a link rendered on initial form paint (edit mode).
     act("copy-jitsi", (e) => copyLink(state.composing.conference, e.currentTarget));
+    act("remove-video", clearVideo);
     act("add-reminder", () => {
       const box = el.querySelector("[data-reminders]");
       const wrap = document.createElement("div");
@@ -1789,7 +1820,16 @@ export default function mount(el, ctx, props) {
     } catch { /* ignore */ }
   })();
 
+  // An invitation answered in Mail (calendar · invite.js) changed the calendar.
+  // Not while a form is open: re-rendering would throw away what is being typed.
+  const onChanged = async () => {
+    await loadEvents();
+    if (!state.composing && !state.confirm) render();
+  };
+  window.addEventListener("webmail:calendar-changed", onChanged);
+
   return () => {
+    window.removeEventListener("webmail:calendar-changed", onChanged);
     el.innerHTML = "";
   };
 }
diff --git a/plugins/webmail_plugin_calendar/webmail_plugin_calendar/ui/ultimo-logo-signet.svg b/plugins/webmail_plugin_calendar/webmail_plugin_calendar/ui/ultimo-logo-signet.svg
new file mode 100644
index 0000000..f5ff865
--- /dev/null
+++ b/plugins/webmail_plugin_calendar/webmail_plugin_calendar/ui/ultimo-logo-signet.svg
@@ -0,0 +1,34 @@
+<?xml version="1.0" encoding="UTF-8" standalone="no"?>
+<!-- Created with Inkscape (http://www.inkscape.org/) -->
+
+<svg
+   width="44.943924mm"
+   height="42.975948mm"
+   viewBox="0 0 44.943923 42.975948"
+   version="1.1"
+   id="svg1"
+   xml:space="preserve"
+   xmlns:xlink="http://www.w3.org/1999/xlink"
+   xmlns="http://www.w3.org/2000/svg"
+   xmlns:svg="http://www.w3.org/2000/svg"><defs
+     id="defs1"><linearGradient
+       id="linearGradient11"><stop
+         style="stop-color:#f89629;stop-opacity:1;"
+         offset="0.20198774"
+         id="stop13" /><stop
+         style="stop-color:#f74176;stop-opacity:1;"
+         offset="1"
+         id="stop12" /></linearGradient><linearGradient
+       xlink:href="#linearGradient11"
+       id="linearGradient12"
+       x1="54.340946"
+       y1="122.84999"
+       x2="54.340946"
+       y2="162.66415"
+       gradientUnits="userSpaceOnUse"
+       gradientTransform="matrix(0.75684298,0,0,0.80151105,3.0076311,94.135157)" /></defs><g
+     id="layer1"
+     transform="translate(-21.70051,-187.41349)"><path
+       id="path1-2"
+       style="baseline-shift:baseline;display:inline;overflow:visible;opacity:1;vector-effect:none;fill:url(#linearGradient12);fill-opacity:1;stroke-width:0.778856;stroke-linecap:round;enable-background:accumulate;stop-color:#000000;stop-opacity:1"
+       d="m 58.875622,191.58757 c -2.152336,-7.4e-4 -4.067804,1.84724 -4.067104,4.1266 v 2.85212 c -0.073,-0.005 -0.146556,-0.007 -0.220195,-0.007 H 44.088203 33.589648 c -0.04176,-7e-5 -0.0835,5.9e-4 -0.125155,0.002 v -2.78918 c -1.66e-4,-2.27807 -1.959264,-4.12477 -4.110377,-4.12494 -2.151113,1.8e-4 -4.208743,1.84687 -4.208908,4.12494 v 15.55127 c -3.9e-5,0.005 -0.02954,3.84339 2.173004,7.60498 2.20396,3.76402 7.038201,7.38257 14.452668,7.38257 h 4.580673 c 7.417703,0 12.26918,-3.66617 14.505859,-7.44221 2.23668,-3.77604 2.27039,-7.63481 2.27039,-7.63481 l 0.0016,-0.0344 V 195.7141 c 7e-4,-2.27872 -2.102019,-4.12642 -4.253744,-4.1266 z m -2.007917,7.94794 v 11.57584 0.0286 c 0,0 -0.06644,2.0824 -1.311391,4.18416 -0.572022,0.96572 -1.445415,2.15762 -2.917676,2.99793 -1.472263,0.8403 -3.460652,1.33079 -6.272222,1.33079 H 41.78535 c -2.82381,0 -4.798635,-0.47938 -6.256969,-1.30429 -1.458334,-0.8249 -2.313565,-2.00343 -2.85901,-2.93496 -1.196636,-2.04365 -1.230039,-4.07193 -1.230039,-4.07193 l -0.0011,-0.0141 v -0.0157 -11.69637 l 0.02191,0.0178 7.82e-4,10e-4 c 0.03515,0.0487 0.07994,0.0958 0.133761,0.14041 l 5.513859,4.57144 5.515036,4.57144 c 0.651946,0.53945 2.279028,0.53945 2.930974,0 l 5.515034,-4.57144 5.514252,-4.57144 c 0.01986,-0.0164 0.03852,-0.0331 0.05593,-0.0501 l 7.82e-4,-8.2e-4 z" /></g></svg>