ITS is aware of an issue with forwarding email from Queen's University to email accounts outside of Office 365.
Queen's mailboxes that have setup forwarding will receive failure messages containing:

Delivery has failed to the following recipients
<Email address listed>
Reason:
Remote Server returned '550 5.7.520 Access denied, Your organization does not allow external forwarding. Please contact your administrator for further assistance. AS(7555)'

The forwarding disruption began to occur overnight Thrusday Jan 7th, the issue was resolved on Friday Jan 8th at 9:15am.

Accounts with mail forwarding enabled should review their Queen's account and re-forward any messages that failed if desired.