M365 Secure score - Turn on the common attachments filter setting for Anti-malware on EOP This filter will help us to prevent certain types of files that are risker to send and receive via e mails. To make sur e these file types don't get through, enable the common attachment filter. How to acces s - https://security.microsoft.com/ then go to Policies & Rules > Threat policies > Anti-Malware It will have a long list You can use the default list of file types or customize it. Messages with the specified attachments types are treated as malware and are automatically quarantined. Change notification status to different organization requirement.