[kkmickos]

I use SA on my own domains and I feel it is as efficient as Google's own spam detection. Although no spam mails slipped through in months, a few legit got caught due to their incompetence in html-emails.

As for ClamAV, their database is updated frequently. It's probably not as good as commercial vendors such as Symantec, NOD32 and so on (can't compare because I haven't used them for years), but I feel it offers some protection.

[A_COMPUTER]

At this point I consider myself a competent SA admin. I've got one particular box with a domain going back to at least 1998 that I can't block enough spam, too much still gets through. SpamAssassin is great, but I've been using GMail since the beta and spam almost never gets through, like single digits for me in all that time.