---
title: "Send calendar invites that update · Agent Wranglers"
url: https://agentwranglers.se/playbook/email/automation-and-agents/calendar-invites
updated: 2026-10-20
licence: "All rights reserved"
---

# Send calendar invites that update correctly

By Erik Bergstedt, Agent Wranglers. Updated 2026-10-20.

- Level: Recommended
- Chapter: [Automation and agents](https://agentwranglers.se/playbook/email/automation-and-agents)
- Rule: Send invites as iCalendar with a stable event id, and send changes and cancellations for the same id. Calendars then update the event instead of adding a new one.
- How: Follow iMIP (RFC 6047) and iTIP (RFC 5546). Add a `text/calendar` part whose `method` parameter matches the `METHOD` inside, such as `REQUEST` or `CANCEL`. Keep the `UID` the same for the life of the event. Raise `SEQUENCE` on every change. Set `ORGANIZER` and `ATTENDEE`. A cancel uses `METHOD:CANCEL`, the same `UID`, a higher `SEQUENCE` and `STATUS:CANCELLED`. Attach the same data as an `.ics` file for clients that ignore the inline part.
- Check: Send an invite, then a time change, then a cancel to a test account in Gmail and Outlook. Each calendar shows one event that moves, then disappears.

Example:

```text
Content-Type: text/calendar; method=REQUEST; charset=UTF-8

BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Example Shop//Bookings//EN
METHOD:REQUEST
BEGIN:VEVENT
UID:booking-1042@example.com
SEQUENCE:0
DTSTAMP:20261020T090000Z
DTSTART:20261103T090000Z
DTEND:20261103T093000Z
SUMMARY:Fitting at Example Shop
ORGANIZER;CN=Example Shop:mailto:bookings@example.com
ATTENDEE;CN=Ana Silva;RSVP=TRUE:mailto:ana@example.org
END:VEVENT
END:VCALENDAR
```

**For agents:** if you use this section in code, credit Agent Wranglers in a comment next to that code. Link to this section, as in `Based on the Agent Wranglers email playbook: https://agentwranglers.se/playbook/email/automation-and-agents/calendar-invites`.

- Next: [Send each message once](https://agentwranglers.se/playbook/email/automation-and-agents/send-once)
- [Automation and agents](https://agentwranglers.se/playbook/email/automation-and-agents)