Excellent! Rated 5 out of 5 stars
This is an excellent plugin. The TB 3 extension from http://www.froihofer.net/fileadmin/downloads/xnote-2.1.0-lf-tb3.xpi works very well. Together with tagging / GTD ideas like http://entropicprincipal.blogspot.com/2005/09/using-thunderbird-to-get-things-done.html this makes TB an excellent GTD tool. Notes are also kept if mails are moved from an IMAP account to a local folder.
Some things that would be great:
a) a Hotkey to add a note
b) a configuration where the note should initially be displayed, and its size
c) a column or tag for notes so that one can filter on mails that have notes.
Thanks and have a nice Christmas,