365 / Outlook - Shared Mailboxes logging users out of main accounts

[ovenchips]

Morning, anyone else having a fun friday with Outlook today?

We're finding that since this morning, when a user tries to open a shared mailbox that they have delegated access to, it'll happily open a new tab and show the mailbox, but it'll kick them out of their actual account on the original tab, then prompt them to try and log back in as the shared mailbox instead of their own account.

 

Happening on multiple devices, across Win 10 / 11 / MacOS, and hitting multiple shared mailboxes in this & other schools.

Screenshot is the popup you get on the main account tab, clicking Refresh tries to log you in with the shared mailbox email.

 

[altecsole]

Is this a real 'shared' mailbox, or a regular mailbox that they have access to? I ask, because I had a similar situation where it was a regular mailbox and the user had signed into the mailbox with the mailbox credentials, rather than as herself. Having her sign out of 'her' Microsoft account fixed the issue.

[ovenchips]

I did double check as we've got a bit of a mix still, but this is definitely a "real" shared mailbox.

[DWilson1997]

We've seen this today too!