I'm looking for a way to configure Sendmail to route messages to selected domains through another MTA instead of trying to do it directly through their correspondent MX records.

My AWS EC2 server sends hundreds of messages per hour but the ones directed to Yahoo and Microsoft domains (hotmail, live, outlook, etc.) are being rejected. I have another server that is not being blocked by MS and would want to use it to send just those ones that the first one can't.

Both servers have a working reverse DNS, DMARC, SPF and DKIM records.

If you're not spamming you can use mailertable
If you do, you'll get your other server also blacklisted

1 members found this post helpful.

Thank you, that is what I was looking for.