Hey all -- I'm on the technical advisory board for MailChannels, a company who make a commercial traffic-shaping antispam product, Traffic Control. Basically, you put it in front of your real MTA, and it applies "the easy stuff" -- greet-pause, early-talker disconnection, lookup against front-line DNSBLs, etc. -- in a massively scalable fashion, handling thousands of SMTP connections on a single box. By taking care of 80% of the bad stuff upfront, it takes a massive load off of your backend -- and, key point, off your SpamAssassin setup. ;)
Until recently, the product was for-pay and (relatively) hard to get your hands on, but as of today, they're making it available as a download at http://mailchannels.com/download/ . Apparently: "it's free for low-volume use, but high volume users will need a license key." Anyway, take a look, if you're interested. I think it's pretty cool. (and I'm not just saying that because I'm on their tech advisory board. ;) --j.
