"On behalf of" reply from a resource delegate to the meeting organizer in Office 365

Applies to: Exchange Online


In Office 365, assume that one or more delegates are added to a resource mailbox, and that a delegate accepts a meeting request. In this situation, the From line of the email message that's sent to the meeting organizer says "<Delegate> on behalf of <ResourceMailbox>." 


When a delegate is added to a resource mailbox through the Select delegates who can accept or decline booking requests option, the delegate is granted "Send on Behalf" permissions. This behavior is by design in Office 365.


Go to the Exchange admin center, and then open the settings for the resource mailbox. In the navigation pane, click mailbox delegation, and then under Send As, add the delegate.

Note Don't remove the delegate who is listed under Send on Behalf. Removing the delegate also removes delegate access.


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