Respond to an event reminder
When an event reminder appears, tap the event description to open the event, or tap one of the following:
Contact Meeting Attendees: If the event has attendees, this opens an email message with their addresses added to the To field. The default message text is "Running late. On my way...". You can edit the text before sending the message.
Dismiss: Close the notification.
Snooze: The reminder reappears in five minutes.
Checked against the LuneOS code and installed apps. Nobody has tried these steps by hand yet, so tell us if something differs.