554 5.6.0 Permanent error while processing message

New Contributor


We have one mailbox with the issue: when the user wants to send an email with an attachement bigger than 1 mb, the servers returns immediatly the error. This mailbox was OK until yesterday...


What can be the issue?



2 Replies


Having the exact same issue.  One random user mailbox.

3.5 hours on with MS support still no resolution.

I am looking at the outbound filters and rules for my org while I wait for MS to call me back again.  Let us know if you get anywhere with this...



I've deleted the recoverable items on the mailbox, and after a couple of hours, all was working fine again