Undelegated mailboxes wont stop auto mapping to User

Hi Everyone, Stumped with this one (and it seems Office365 Support are too), I thought I would give it a try here. The environment used to run on Exchange 2013 On premise, now runs 365 Synced...

exchange

office 365

VasilMichev
Jul 23, 2018
You can try using the –ClearAutoMapping flag for Remove-MailboxPermission, I've posted some examples here: https://www.michev.info/Blog/Post/1382/removing-automapping-and-resetting-default-mailbox-permissions-in-exchange-online

If those mailboxes previously existed on-premises, you might need to clean up the AD attributes as well, msExchDelegateListLink in specific.