youds
Verified User
I just want to add to this that you can already run both your own separate outgoing email server for all outgoing email (access it on non-standard port for security, and then firewall off all outgoing traffic to destination port 25 on your DirectAdmin server). You can carefully examine all outgoing email on that server (which will have plenty of resources available to do it) to make sure it's mail you really want to send.
Incoming email is a bit more difficult, but folk have already posted on these forums examples of how to do it, keeping the incoming server aware of all valid email addresses on the new server, copying over certain files and directories to a DirectAdmin-like structure on the outgoing mail server.
You can also buy commercial products specifically designed for both incoming and outgoing email, which will still manage final email delivery on your DirectAdmin server.
Or you can re-skin DirectAdmin, ignore the DirectAdmin mail stuff except for mail to the domain owner user accounts, and manage your own email elsewhere.
Some possibilities include:
Zimbra
Vexim
Jeff
I think I'll be doing this for the forseeable future