SMTP ghost/intercept?

Dear All,

I am trying to play Civ 4 via email with a friend of mine. Unfortunately we both have gmail accounts, which utilise port 587 (i think) while Civ 4 is locked in to using port 25, apparently an old default setting for ISPs SMTPs. My question is, is it possible to have a piece of software act as a psuedo SMTP server between Civ 4 and my actual gmail account? In other words could I install something that Civ 4 would think was my actual SMTP server (on port 25 etc) and then this could automatically forward the email to the correctly through the gmail system?

Thanks in advance

Tim