I've got SSMTP on a linux server for sending outgoing mail via gmail.

But I've got a couple of useless windows programs (UPS) that are expecting a port 25 SMTP server to post to.  One of them is currently working with xtra, the other I can't get to go.

So I thought if I ran a local smtp server on my linux, to then forward to the external email addresses for my UPS management.

Can someone let me know a simple SMTP server that I could do this with?  The SMTP server does not  need external access.  If I can't forward, then I script a log reader to email the received email if I have to.

But if someone knows how to get the forwarding working that would help also.

I'm not adverse changing mail product, but simple is best.  the only thing this machine currently emails is when package updates etc are ready and the state of the odd job.