I don't know if I'd call that a slave unless you want to automaticallly pick up all the settings from the DirectAdmin server and duplicate them on the mail server every time thre's a change.Just want to move my mail server (exim, clamav and spamassasin) to another server.
mr.applesauce is being a bit simplistic; that's the first step you need to take.Server 1: DA Installation with apache, php, and users data (site + email data)
Server 2: MySQL Server
Server 3: Exim server, clamav and spamassasin
In other words, I would like to move the mail processing threads to another server - receiving and sending about 10.000 mails / day - a separate mail server is a must.