Considerations / Limitations for Microsoft 365 Shared Mailboxes


How do Microsoft 365 (Exchange Online) shared mailboxes differ from the previous Legacy Exchange shared mailboxes?


  • When sending emails from Outlook, the default from address (your UTD account) will always be the account sending the email even if you are selected on the shared mailboxes inbox.
    • However, if you are replying to emails from the shared mail’s inbox, it will automatically use the shared email.
    • To send new mail from the shared mailbox, you must select the shared email address from the drop-down when composing the message.
  • When sending from a shared mailbox, a copy of the sent message will be stored in your mailbox Sent Items and the Sent Items of the shared mailbox.
    • The above cannot be changed.
  • When composing an email on Outlook for Windows, you cannot set a default signature for the shared mailbox.
    • If you have multiple signatures in Outlook for Windows, you can right-click the signature displayed to switch quickly.
  • When adding a shared mailbox to the Outlook app, you will not receive notifications for the shared mailbox.
    • The above cannot be changed, but you can work around this by right-clicking the folders you need notifications from and selecting Show in Favorites.

Screenshot of the options for a folder highlighting the "Add to favorite" option

  • Adding a Shared Mailbox on the mobile app will enable push notifications. This can be disabled in the Outlook Mobile app settings in the Notifications area.


Article ID: 261
Mon 11/22/21 12:46 PM
Tue 11/14/23 12:11 PM

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Shared Mailboxes or System Mailboxes are mailboxes critical to department business processes and are often use to facilitate department and/or mass communication.  Shared Mailboxes are accessed by multiple users at the same time.