Using Custom Headers for email delivery

If you are using third-party filtering software or have issues with email delivery, you may need to utilize Microsoft Mail Flow Rules.

A more relevant version of this article can be found at step 8 of manual allowlisting.

1. Navigate to https://admin.exchange.microsoft.com.
2. Go to Mail Flow > Rules section of the portal.
3. Create a new Rule.
4. Name the rule and set the conditions for utilizing the headers, as shown below.