Just completed a transition of birdhouse hosting to a new machine (in the same data center) with a greatly increased monthly bandwidth ceiling, and have been able to raise bandwidth caps for all customer account levels.
Also took the opportunity to upgrade SpamAssassin to version 3, which, among other enhancements, supports SURBLs — Spam URI Realtime Blocklists. SURBLs essentially use the same logic as Movable Type’s blacklisting system – rather than trying to analyze content or block sender addresses or IPs (which are moving targets), SURBLs hit spammers where it hurts by blocking messages that include blacklisted URLs.
The downside of using SURBLs alone is that messages containing URLs that are not yet blacklisted slip through the net. But by combining SURBL scanning with content analysis, and by using distributed/collaborative blacklisting systems, you end up way ahead of the game.
Had to modify some of my customer’s SpamAssassin rulesets to work with the new syntax in SA3, but now that we’re dialed in, spam blocking seems to be more effective than ever – we’re catching about 98-99% of unwanted mail prior to delivery. w00t!