Apple/iCloud Calendar: reminders.use_default is false but reminders.overrides is empty in event.created/event.updated webhook payload (iPhone alert set)

Question and Answers
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1

I’m working on Nylas v3 calendar webhooks (notifications). I’m seeing a consistent issue only with Apple Calendar (iCloud) events created/edited from iPhone Calendar.

Important context (organizer vs attendee)

  • Organizer: an Apple Calendar/iCloud user, not linked to Nylas (not a Nylas grant).

  • Attendee: an Outlook/Microsoft user that is linked to Nylas (this is the grant receiving the webhook).

  • The event is created from the organizer’s iPhone (Apple Calendar app).

What is the isuue

When the organizer sets an alert/reminder in iPhone Calendar (ex: 30 minutes before), the webhook payload received for the Outlook attendee grant includes:

  • reminders.use_default: false

  • but reminders.overrides: [] (empty array)

This feels inconsistent because I’d expect an override like “30 minutes before” to appear when use_default is false.

2

Hello

This is expected behavior, not a bug.

What’s happening:

  • The organizer’s 30-minute alert is stored in their Apple Calendar only.

  • When the Outlook attendee receives the invitation, they receive their own reminder settings.

Reminders and alerts are per-user settings and are not shared between the organizer and attendees. The organizer’s alarm does not propagate to invitees through the iCal invitation in a way that Microsoft preserves.

The Outlook attendee will need to set their own reminder on the event if they want one.

Many thanks,
Samuel R.
Support Engineer, Nylas

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