Quote:Microsoft urges both administrators and users to not bypass the built-in Microsoft Office 365 spam filters in a support document published today and it also provides guidelines for cases when this can't be avoided.
 
Office 365 admins and users should avoid enabling Allow or Block lists in the Spam Filter policies and skipping Transport Rules scanning according to Microsoft.
Additionally, toggling on Safe and Blocked senders is also not recommended for Outlook or Outlook on the Web users and admins.

"We recommend that you do not use these features because they may override the verdict that is set by Office 365 spam filters," says Redmond.
 
Preferably, Microsoft advises Office 365 customers to report junk email messages for analysis with the help of the Microsoft Junk Email Reporting Add-in "to help reduce the number and effect of future junk email messages" — Outlook users can report junk email using the Report Message add-in.
 

Reporting junk email (Image: Microsoft)