Invitations might be sent twice from an Outlook mobile app when a new attendee is added to a meeting

Last Updated: April 10, 2025

ISSUE

When a new attendee is added to a meeting using Outlook for Android or Outlook for iOS with Exchange on-premises mailboxes, the invitation might be sent twice from the Outlook mobile app. 

After adding the attendee, a duplicate event appears in the attendee's calendar. A duplicate invitation will also appear in the organizer's outbox.

This issue only occurs with Exchange on-premises mailboxes. This issue does not occur with users who were added when the meeting was initially created. 

STATUS: INVESTIGATING 

The Exchange Calendar Backend team is investigating why adding new attendees through Outlook for iOS and Android is causing duplicate invitations to be sent. We will update this topic when we have more information about any potential future changes. 

WORKAROUND
 
To work around the issue, add the new attendee to the meeting using OWA or Outlook for Windows.

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See Also

Fixes or workarounds for Outlook for mobile