Since the beginning of the year, I’ve noticed that I had started to catch good email in my Mac OS X Server’s email spam filter. It was odd, since it generally works quite well, and rarely catches any “false positives.” This morning at my office, one of the guys I work with was having to patch one of our systems because of a “Y2K10 bug” where the date isn’t interpreted correctly. Later, I noticed on Slashdot there was a story about the Y2K10 bug affecting a large number of systems around the world. I did a quick search for Spamassassin, and found that it was suffering from a bug in a date rule! Apple has a technical note on the issue: Mac OS X Server v10.5 and 10.6 use SpamAssassin to filter “spam” from inbound messages; SpamAssassin includes a rule that increases the spam score for any inbound message sent on or after January 1, 2010. This increased score may cause some inbound messages sent on or after January 1, 2010 to be inadvertently filtered as spam. There is an updated spamassassin rule that fixes the problem as well. Run the command: sudo sa-update –nogpg to apply the new rule. The –nogpg flag is needed for OS X Server since it doesn’t have GPG installed by default.