Postfix: What does "If your machine is a mail server for its entire domain" indicate?

by myNewAccount   Last Updated May 23, 2020 00:00 AM - source

Environment: Postfix 3.3, Centos 8, Digital Ocean Droplet

I'm reading the Postfix basic configuration readme and I came across a definition I don't fully understand.

Under the heading, What domains to receive mail for it goes over the mydestination parameter and includes this sentence,

IMPORTANT: If your machine is a mail server for its entire domain, you must list $mydomain as well.

I believe that warning is referring to this line in Below is the default value.

mydestination = $myhostname, localhost.$mydomain, localhost

Unfortunately I'm not exactly sure what that warning means.

On my server I have an NGINX reverse proxy, a Node.js Express server and the Postfix/Dovecot setup.

Question: Because I only have a single mail server does that mean it covers my whole domain and I need to use $mydomain? Or are they saying that because I also use the server as a web server the mail server doesn't represent the entire use of the domain and I shouldn't include $mydomain? Does it mean something else? I can't tell what they mean.

Answers 1

Not necessaryly, you can delegate a mail destinated to a subdomain to another server. For for instance: use a diferente server than that's mean you are using two postfix server.

If you set:

mydestination = $myhostname, subdomain.$mydomain

You are saying "OK Accept mail destinate to "hostname" and

Edited: You can use a diferente public IPs for each postfix server or subdomain.

May 23, 2020 00:55 AM

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