How Can I set up a relay between my dedicated servers??

I am running Exim in cPanel 60, my trouble is one of my VPS nodes has port 25 blocked upstream & I need to get around it. I have other VPS nodes at other locations that do not have port 25 blocked. So I am wanting to set up an SMTP relay using “smart host” between my dedicated servers.

What do I need to know setup-wise for the side receiving the outgoing email as well as ultimately sending it?

Regards
Shami Andrew

[i]Unnecessary links to those 2 sites removed by moderator.[/i]