[CentOS] Postfix Configuration Setup for 2+ domains

[Rick Barnes]

Hello,

I have a client that wants to have a dedicated smtp sending host. But
they have 2 separate domains then that don't want to have share IP
address. The reasons from this is long and drawn out.

Is it possible to setup postfix in a virtual host config, like apache
for example, such that, domainA.com listens and sends on one IP address
and domainB.com listens and sends on another address.

This host is simply a email forwarding host, so no user accounts are on
the server, they have about 5 servers serving websites for 2 domains and
subdomains and want email coming from a common source for both domains
(this will be the relayhost for the web servers).

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

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.

I can find info on virtual domains, but its geared for receiving email
for multiple domains.

Thanks,
Rick