Emails being returned undeliverable

IT Services has become aware that there was a problem delivering some email messages sent from Office 365 to students or to ourside the University.  The message would appear to be sent normally, then after two days would be returned to the sender as undeliverable.

This problem was caused by a change in the Office 365 email system that resulted in the messages being blocked by our anti-spam controls.  We have adjusted our system and all remaining and new messages will be delivered normally.

This problem only affected a small percentage of messages sent from Office 365, is only used by faculty and staff. Students use UWinGmail and would not have been affected.