Qmail with Multiple Domains

[TechSpa]

Using Plesk 9.0.1 we host several domains, each with their own MX record "mail.client1.com", "mail.client2.com". The server is configured with a hostname of "web01.company.com". In short our problem is that email 'sent' from the server always originates from "web01.company.com". Is there a way we can get it to originate from "mail.client1.com"???

 

[TechSpa]

After some more research, it seem like I'm wanting to 'bind' certain virtual domains to IPs. If a message comes in an IP, the reply should go out the same IP. Anybody got any ideas?

And information/links is appreciated!