Custom anti-malware policies not working (solution)

Hi all,

I want to share the solution regarding custom anti-malware policies not working. The purpose of my custom policy was to quarantine messages with htm, .html files attached to them because they are often used in phishing campaigns. Messages kept being delivered in the INBOX and not quarantined.

Solution: after weeks of troubleshooting with Microsoft support, we found out that you can't use preset policies if you want custom policies to work.