[ms office - o365] Shared mailbox archiving recent emails

[jmak]

We're having an issue with an Exchange online shared email account where recent (today's) emails are being archived. It started yesterday morning, then apparently stopped yesterday evening, but restarted this morning.

 

My current guess is something that one of the users has set. I've removed all users apart from one and it looks like the problem has gone.

 

The only change I'm aware of is that one of the users got a new iPhone yesterday. Is there a setting I need to check?

 

Alternatively, is there somewhere I can prevent changes to archive settings being changed?