Message Meetup event attendees about a last-minute change

1. Open the event from Your Events on the Meetup website, click Organizer tools, then Edit event.
2. For an event that belongs to a Meetup repeating series, pick Edit this event only, change the location or start time, and click Save changes.
3. Go back to the Meetup event page, open the Organizer tools dropdown again and choose Contact attendees; on the Android app it sits in the organizer menu of the event.
4. Write the message by hand, repeating the new room or time you just typed into the form. People who RSVP after the message is sent never get it, and checking that the edit and the message say the same thing is on you.

Tonight's Python Night moved to room 204 and starts at 19:30. Update the event and message everyone going.

1. 01

   Find the right event

   list_events with upcoming returns today's events for the group. With two events on the same day, the agent asks which one instead of guessing from the title.

2. 02

   Compare before editing

   get_event shows the current venue and start time. When the event already shows the new room, the agent skips the edit and only writes the message, so a second run does not change anything twice.

3. 03

   Edit only what moved

   update_event gets just the changed field, for example the venue or start_time. When the event is part of a repeating series, the agent says first that Meetup will split this date from the series, and waits for your OK.

4. 04

   Write the message from the edit

   The subject names the change and the date ("Room 204 tonight"). The body repeats the new room or time exactly as saved, plus what stays the same. You read it before message_attendees sends it to everyone going.

5. 05

   Report who was not reached

   The reply gives the recipient count from Meetup next to the going and waitlist numbers from list_events. Waitlisted members are not part of the message, so the agent says how many there are.

Python Night #24, Thu 12 Nov 2026, Tech Founders Berlin.
Venue changed: Co-Work Mitte, room 112 > room 204. Start 19:00 > 19:30, end moved to 21:30.
Message "Room 204 and 19:30 start tonight" sent after your OK to 38 attendees.
4 members are on the waitlist and did not get the message.
The event was part of a monthly series; this date is now a standalone event.

• When the start time of a Meetup event changes, Meetup moves the end time to keep the duration that was set, two hours by default.
• Meetup event hosts can manage attendees, contact attendees and edit event settings for their event without being on the group's leadership team.
• Meetup can reject an edit to an online event with "Sorry, there was a problem editing this event" when the Add link field holds an unsupported link; Meetup suggests putting that link in the description instead.
• Meetup sends organizer messages by email with a gray border and the Meetup logo, and recommends plain text with images no wider than 360 pixels.
• Meetup event comments are capped at 700 characters, so a longer change notice belongs in a message to attendees.

update_event and message_attendees ask for your OK by default. To run it on a schedule without you, switch confirmation off for those tools in your dashboard.

Sources: Meetup Help: How do I contact my members? · Meetup Help: Editing a Meetup event · Meetup Help: Editing a repeating event · Meetup Help: Issues when editing an existing event

curl https://cotlet.dev/api/v1/meetup/message_attendees \
  -H "Authorization: Bearer $COTLET_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"event_id":"311988140","subject":"Room 204 and 19:30 start tonight","body":"Python Night moved to room 204 at Co-Work Mitte and starts at 19:30. Same building, same talks."}'

{
  "event_id": "311204587",
  "status": "sent",
  "recipients": 38
}

MCP: add https://cotlet.dev/mcp/v1 with the same key; the tool is meetup_message_attendees. Example data.

• Create a series of Meetup events from an agenda
• Mark Meetup no-shows after an event
• Meetup API and MCP server: every tool
• All use cases