New owner_email field on Microsoft calendars

August 18, 2026Calendar

Microsoft calendars now come back with the email address of the account that owns them. Until now, is_owned_by_user told you whether a calendar belonged to the authenticated user, but nothing told you whose it was when the answer was no. That mattered for Microsoft grants, where a single user often has a dozen shared calendars in the same list response.

Added

• owner_email on the Calendar object returns the email address of the account that owns the calendar. It appears on every Calendar response: Get all Calendars, Get Calendar, Create Calendar, and Update Calendar.

  {
    "request_id": "2245305189-f1252288-9798-4e67-8201-xxxxcbdfc000",
    "data": {
      "name": "Calendar",
      "hex_color": "",
      "grant_id": "9564c95c-32f0-47cc-xxxx-fd1e961b910a",
      "id": "AAkALgAAAAAAHYQDEapmEc2byACqAC-EWg0ASdP2iK6fm0aDwISla-4q0QAAAAARxxxx",
      "object": "calendar",
      "is_primary": true,
      "read_only": false,
      "is_owned_by_user": true,
      "owner_email": "[email protected]"
    }
  }

• owner_email in calendar.created, calendar.updated, and calendar.deleted notifications, so you can attribute a shared calendar to its owner without a follow-up read. See the Calendar notification reference.

Notes

• Nylas returns owner_email for Microsoft grants only. Google, iCloud, EWS, and virtual calendars omit the field, so treat it as optional rather than assuming it’s on every Calendar object.
• The field is read-only. You can’t set or change it with a PUT request, the same as is_owned_by_user.

Updated docs

• Using the Calendar API explains the field, its Microsoft-only behavior, and how it pairs with is_owned_by_user.
• Create and list calendars mentions it in the calendar flags section.