I installed a registered copy of SpamSieve and tried to start using it today. I restarted Apple Mail after the SpamSieve plug-in was installed but now Mail shuts down immediately after the main window is displayed. What gives?
Probably the crash was caused by another Mail plug-in that was enabled when you installed SpamSieve’s plug-in. Please check the folders:
and move the non-SpamSieve plug-ins to the desktop, then re-launch Mail.