smtp server and relay

Hi!.

I have a server acting (among other things) as mail server and mail list server.

Time ago I had it delivering mail directly, but some time ago I had to set outgoing mail through a smart smtp server which allow relay (different email FROM) because of bounce problems. Im planning to stop using this smtp server for some reasons and I'm wondering if it's possible any other kind of solution or if anyone can suggest some smtp servers with support relay (even if I have to pay for it).


thanks