Guys, Here is my Q...

Are there any opensource E Mail Relay Servers ready to get in, instead of Sendmail / Postfix Servers (I don't know how to !!!)

My requirement is, I have couple of servers with no internet facing, from where my applications generate E Mails and those have to route through a Server (E Mail relay Server). Is there any solution for this.

Please guide me in detail if there is a way in Postfix, by having a postfix Server in DMZ & what are the configurations i need to do at client side (No onternet facing Servers)

Appreciate your time


Thanks
Wannabe Techie