Routing Outbound Mail Through External SMTP Server Using Certificates

Copper Contributor

Hi, I'm a junior developer and trying to route all outbound mail for my Microsoft 365 domain using a Connector to a postfix server using a digital certificate. How can I do this?


I can successfully set up a connector using Office 365 to Partner Organization, specifying my relay hosts as smart hosts, and "Always use TLS".


I'd like for Microsoft 365 to send all outbound mail through our servers, not just those for my domain, so I've set "*" for the "only when email messages match ...".


The problem is with the digital certificate - how do I upload or specify a digital certificate to be used as a way to authenticate the host?


I'd like to generate the certificate keypair on the Linux/postfix side, then upload the private key and public certificate or a digest as a way to authenticate the Microsoft 365 server as athorized to relay mail through our postfix mail server.


Of course I will configure the postfix mail server (it's far easier than the Microsoft 365 side, so it seems).


1 Reply
No one has any ideas on how to manage certificates in Microsoft 365? Is there a more appropriate place I should go to ask this question?