Back in November, I posted about a free greylist transport sink that works with Exchange 2003, Exchange 2000, and the IIS SMTP service. I've been using it steadily at home and have continued to be impressed by it, especially when my Exchange server went offline just before I went out of town and I was forced to put up a quick workaround of IIS SMTP + the greylist service. With greylisting as my anti-spam defense, we were still knocking down the majority of incoming spam attempts.
Here at 3Sharp, we recently changed our anti-spam strategy and I went to the GRYNX greylist site to grab the latest version (1.2.4) available at the time. Man, did I receive a pleasant surprise: it now supported storing the triplet database in a Microsoft SQL Server database! Just a few short minutes later, I had a database created, configured, and up and running. Using this in conjunction with the IMF, we've once again knocked our spam down to "minor irritation" levels.
This version will work against SQL Server 2000 or SQL Server 2005, hosted either on the same machine or a remote machine (so you can use a central database server to store a shared triplet database for multiple bridgehead servers -- how enterprise!)
Thanks, Chris!
Updated 11 Sep 2007: The author has just let me know that the product is now called JEP(S) and is available from a new website. Link updated accordingly.