I’m currently trying to set up Mailcow as a smarthost for an Exchange 2013.
Setting the DynDNS of the Exchange as Forwarding Host and setting the send connector to anonymus, results in an error “relay access denied” by Mailcow.
If I set authentication with a Mailcow user, who is allowed to send for the entire domain, It get “Require basic authentication”.
If I set the authentication to TLS, I get “Untrusted Root” (even though I am using Let’s Encrypt).
Maybe I’m doing the whole thing wrong but basically I just want to send mails from my Exchange 2013 via Mailcow.