I have a postfix server, "Server."

It is acting as the SMTP server for 2 domains, domain1.com and
domain2.com.

I need "Server" to relay mail from domain1.com to another SMTP server,
"RealSMTPServer," while distributing domain2.com mail as usual.

Alternatively, I could also relay domain2.com to "RealSMTPServer2."

Any on how to do this would be appreciated. Thanks very much.


Ian