Mail/spam settings on a server.
Greetings! have been "trolling" these boards for over a year now, and have finally registered.Allrighty, so I have a question that I'm sure comes up rather frequently among those who manage a hosting business, or a server for a handful of design clients. Where is there good step-by-step documatation on how to properly set up or "fine tune" your mail settings on a unix server using whm? (rather than leaving them on default settings.)
In other words, what are some basic steps that I, the admin can do in order to protect the server from mail bombs, spam etc.? I have root access to a vps server and I'm expecting to have a fairly decent increase in design clients over the next 6 months, so I know that spam is an unfortunate high probablity at some point down the road.
If anyone knows "off the top of thier head perhaps some basic tips and/or points to the above, feel free to paste them here. I'd be very obliged.

Btw, I must say that I've learned a lot from WHT in the past year alone, and I think it's an imeasureable value to anyone interested in this business.
Cheers,
Devon