We've just had the Microsoft 365 plugin setup and configured on our Netvault 13.0.3.6 server and everything seems to be working ok apart from a single mailbox is failing to backup, it comes up with an error in the job logs. We can't find anything unusual about the way this mailbox is setup, it is a user mailbox, and the job logs don't provide any help other than the backup failed for this one mailbox.
Has anyone seen this before?