I have been troubleshooting random emails arriving in inboxes, 5 users, that are in mime format, and yesturday, a blank email as well.
I have focused on one pc, and after removing Bitdefender, I believe the problem went away.
I think.
I just got notified that when an outgoing email is sent and the laptop user is CC'ed in, they are gettinng the MIME formatted email, and as Bitdefender is still on that senders pc, it could be effecting the outgoing emails too.
I have tried many things, repair PST,
Update Office 365
Update windows
Disable Bitdefender.
Remove Bitdefender
I have now run out of ideas.