Shared Mailbox Not Syncing. Incorrectly Stating it is Full. (Outlook for Mac)

Question

A user in my org is encountering an issue with her Outlook for Mac:

A shared mailbox was incorrectly showing as full, and as a result it cannot send or receive messages or meetings. Outlook would warn the mailbox was full in the left pane, and would throw an error if a meeting was created or an email was sent.

I have done a deep clean of Office on the Mac, and reinstalled Office from office.com. (Uninstalled apps, and cleared all residual files.)

The issue persists, except now there are no more errors. Instead it quietly fails to send/receive, without alerting the user.

The issue is only seen on her local Outlook client. The owner of the mailbox has no issues with it on his Mac. The mailbox works properly in her OWA, as well.

Please let me know how to proceed.

Answer 1

Dear PB_Tech,

Good day! Thank you for posting to Microsoft Community. We are happy to assist you.

It seems like the issue is specific to the user's Outlook for Mac client. Here are some steps you can try to resolve the issue:

1. Check if the user's Outlook for Mac client is up to date. If not, update it to the latest version.
2. Remove the shared mailbox from the user's Outlook for Mac client and add it back again. To do this, go to Outlook > Preferences > Accounts > select the account that has the shared mailbox > Advanced > Delegates > remove the shared mailbox > click the "+" sign to add it back again.
3. Clear the cache of the user's Outlook for Mac client. To do this, go to Outlook > Preferences > Accounts > select the account that has the shared mailbox > Advanced > click "Empty Cache".
4. If the issue persists, try creating a new Outlook profile for the user. To do this, go to Outlook > Preferences > Profiles > click the "+" sign to create a new profile > set the new profile as the default.

If none of these steps work, there is some possibility that something is wrong at the service backend to make the shared mailbox to sync incorrectly into Outlook for Mac. In this situation, would you please (use admin account) to go to Office 365 Admin Center-> Support-> New Service Request. The support engineers there have the correct escalation channel, and this is the most efficient way to report such issue. You can refer to this article to check the way how to raise a ticket: Ways to contact support for business products - Admin help. The engineers in related team have higher permission and resources than us to help check the root cause from background directly.

I hope the information above can help. If there is any update or I misunderstand you, please feel free to let me know. I will continue to assist you. Your understanding and co-operation are highly appreciated.

Thanks for your precious time. Have a nice day.

Sincerely,

Sherry | Microsoft Community Moderator