Change quote and reply format: to have a real reply header with date, sender, subject etc
Quote Colors: set different colors to different levels of reply
QuoteCollapse
Check and Send
Correct Identity
Image Zoom: unzoom images that do not fit in the window
Enigmail: OpenPGP encryption and authentification
Lightning: a calendar
Remove duplicate messages (Alternate)
Remember mismatched domains
WebMail
Mailbox Alert: to trigger customized alerts for some folders
StartupMaster: only ask your general password once at start
Mail redirect