[CentOS] Postfix Configuration Setup for 2+ domains

[Christopher Chan]

> I have it setup to listen to 2 ip addresses but as of now I get:
> 
> 220 smtp.domainA ESMTP Postfix
> 
> on both addresses. Is there a way to have one address show as:
> 
> 220 smtp.domainA ESMTP Postfix
> 
> and the other:
> 
> 220 smtp.domainB ESMTP Postfix

You can achieve that in master.cf.

IPA:smtp      inet  n       -       n       -       -       smtpd
         -o mail_name=smtp.domainA
IPB:smtp      inet  n       -       n       -       -       smtpd
         -o mail_name=smtp.domainB

> 
> More importantly, email send via 1 should look like it came from that
> domain and email sent to the other look like it came from its domain.
> 

You have to be a bit more clear on this. As an example, do you want 
userA uses YahooA via your server to have his YahooA address rewritten 
to his userA address and emails from userA must also leave your box via IPA?

Or do you want if userA sends mail via IPA with another domain's addy 
other than userA, reject?

Or do you want postfix to log domainA emails with smtp.domainA name and 
likewise domainB emails as smtp.domainB?