SpamSieve is fully compatible with Mac OS X Tiger (10.4 through 10.4.3), however Apple Mail users with 10.4.1 or later must use SpamSieve 2.3.1 or later. When you first update to 10.4.2 or 10.4.3, Mail may uninstall the SpamSieve plug-in. The next time you launch SpamSieve, it should re-install the plug-in automatically, or you can do this by choosing “Install Apple Mail Plug-In” from the SpamSieve menu. The next time you launch Mail, you should see the SpamSieve commands in the Message menu.
After updating to Mac OS X 10.4.3, your mail program might not be able to find and launch SpamSieve. Manually launching SpamSieve once by double-clicking its icon in the Applications folder (not by clicking the Dock icon) should fix this problem.
Several SpamSieve users have reported Apple Mail crashes and other anomalies since updating to Tiger. In all cases, this was caused by Mail plug-ins other than SpamSieve’s. Deleting the /Library/Mail/Bundles/PGPmail.mailbundle or ~/Library/Mail/Bundles/ODMailBundle.mailbundle file stopped the problems.
If you are using MailTags with SpamSieve, make sure that you have the latest version (1.1 as of this writing) or spam messages might not move to the Spam mailbox.