I'm trying to set up a Postfix server (any other software would be ok for me as well). I don't have a static IP, and that can apparently be quite a problem for e-mail purposes: I managed to "send" mails with the default configuration, but the dynamic IP is immediately rejected by any target I try to mail.
Now, DynDNS (which I already use for the domain) offers these things called gateway Mail Exchangers: mx1.mailhop.org, mx2.mailhop.org
; I take it that these are basically fixed-IP proxies that solve exactly this kind of dynamic-IP trouble (plus some spam-protection stuff).
Unfortunately, I have absolutely no clue as to how I'm supposed to set up Postfix to actually use these things. MX
appears to be some kind of "record" that tells other SMTP servers where to find mine, but I haven't found anything about this in the Dyn-account settings. And the postfix documentation has a lot to say about various relays, but is this like a firewall, a LAN, or what?
I would be greatful about any clarification how it all works, ideally /etc/postfix/main.cf
instructions.