Appologizing up front, because I'm not a Linux server admin... AT ALL..., but I'm trying!

I've installed xampp on my Red Hat server, and as far as I can tell, my sendmail is setup. I'm able to send mail internally on the server; however, that isn't what I really want to be able to do.

I understand that sendmail is a mail engine that will distribute emails, but what I want to be able to do is configure my server to connect to my domain server and route emails through there.

In other words, I have a domain name registered by FXDomains, and with that I have email accounts established. I've got an eCommerce server running on my Red Hat Server so that when someone uses my domain name, it takes you right to my eCommerce.

As someone registers or anything happens on that eCommerce server, i'd like for the email to be sent from the eCommerce server to the appropriate location, but if replied to, it would go to an account that is on my FX Domain. right now, it wont even send an email out...

Any help would be greatly appreciated!