Postfix will do it with a virtual alias and a transport map sending selected addresses to a second server.
virtual_alias_map:
Code:
sales@domain.com sales@server2.domain.com
support@domain.com support@server2.domain.com
transport_map:
Code:
server2.domain.com smtp:server2
Alternatively you could use simple aliasing which would work in postfix and sendmail to send the mail to server2:
/etc/aliases:
Code:
sales@domain.com sales@server2.domain.com
support@domain.com support@server2.domain.com
Either way you can't tell the world to send mail to different servers based on username alone. The mail has to go to one server where some of it is filtered and resent.
If at all possible don't do this. Do as vonskippy's suggests and use two domains. It makes the configuration so much simpler and complexity causes failures. One domain could be a subdomain of the other. E.g.
sales@mycompany.com,
my.name@people.mycompany.com.