SLS Email Host or Hosting service

I found the built-in spam filtering in OS X Server to be quite effective for me. It incorporates 3 basic parts, all optional: First it checks one or more RBL lists to eliminate known spammers; second is uses spamassassin to filter out or mark suspect spam; and third it graylists remaining mail (on by default). This is very effective eliminating mail sent by spambots and other non-compliant mail senders. It does add a slight delay (minutes), especially when starting it up. But it is a very effective weapon in the battle plan (a little tricky to turn off graylisting if you want, but possible).

Not counting the ClamAV anti-virus scanner.

Are you looking for a recommendation on an outside anti-spam service?... This is probably the wrong place to ask about that. But you certainly could try OS X Server's built in spam filtering first and try something else if it doesn't work out for you. Personally, for me, OS X Server eliminated (or marked) virtually all spam. In fact, for a while I was concerned that my mail server was even running, since it had been so long since I received any mail 🙂.

Suggested outsourced spam checkers are: MXLogic (www.mxlogic.com) and Postini (www.postini.com). They will relay your messages and provide you of being blacklisted.

They are not free, though.

(info taken from: +Apress-Beginning Mac OS X Snow Leopard Server+ book).

Regards,

Kostas