[Baffles]

I think you're going about this the hard way. I used to do something similar, then I switched to google apps (gmail for your domain) and have never looked back, as TurboFool said.

Is there any reason you don't want to take that route?

Also, you should be able to set your default reply-to settings in your settings at gmail, and any mail you send using their smtp should follow those settings.