On Mon, 22 May 2023, Tom Reed via Postfix-users wrote:
Given the case that: 1. postfix is a backup MX for foo.com 2. this postfix uses other MTA as relay_host When the primary MX for foo.com is down, messages to u...@foo.com will be delivered into backup MX. And, backup MX delivers the message to relay_host, which find that primary MX can't be reachable, so relay_host deliver message to backup MX again.
I think the idea is that the MX for a given domain is expected to accept the mail, rather than relay it somewhere else. (Otherwise the other host should be the MX).
But obviously, if your "other MTA" decides to send the mail to your "backup MX" then I'd say you can have a loop.
Will this delivery loop happen in real world?
My world is only a very small subset of the real world :), but in that world, if I say that a given server is the MX for a domain, then that's that, it should not relay further.
Maybe others with more experience and/or a wider world can provide better info. Cheers. PS: Why do you (think you) need a backup MX? _______________________________________________ Postfix-users mailing list -- postfix-users@postfix.org To unsubscribe send an email to postfix-users-le...@postfix.org
