Ako som písal aj pod článok je spôsob ako opäť spustiť Mail pluginy pod 10.6.4. Mám to odskúšané Widemail aj growlMail fungujú.
Go to ~/Library/Mail/Bundles/ or ~/Library/Mail/Bundles (Disabled)/
open plugin and go to Contents/Info.plist in a text editor Or Property List Editor
Underneath the SupportedPluginCompatibilityUUIDs key, add the following strings:
E71BD599-351A-42C5-9B63-EA5C47F7CE8E (Item 6)
and
B842F7D0-4D81-4DDF-A672-129CA5B32D57 (Item 7)
Save, restart Mail.app