What do other hosts think about the spamhaus sbl list and using it to block emails at the mailserver level? We use all kinds of tools and software for spam protection for clients, but have found that the SBL by spamhaus seems to be the most conservative and only blocks the really hardcore spamming networks, and not have any false positives that block out legit emails. Using it on a test server seems to block 25% of all spam received, which is quite a good percentage.
