When I enable HTTPS Content Filtering in our SonicWall CFS, connectivity to Office 365 breaks very slowly. It might be fine for awhile, but randomly some users start to have Outlook issues where it says "trying to connect" at bottom of Outlook but eventually it says "disconnected", and then no mail comes down.
I have added all domain names listed here
to the Allowed Domains list, in every permutation like https://
, *., and just as shown on those links, but Outlook still slowly fails. To get everybody back up running, I have to go back into the CFS and disable HTTPS Content Filtering.