I need an add-on for Thunberbird 12 which lets me share notes with other users with my same IMAP e-mail account. On Thunderbird, there is no decent add-on to stick notes to an e-mail which automatically pops up somewhere, when the e-mail is selected. On top of this, it's impossible to share it with other users: my team needs to exchange information while receiving the same e-mail in an IMAP account, for instance I give instructions to one employees without an e-mail forward. We use tags to update the status of the assignment associated to the e-mail, but we can't share instructions, i.e. notes.
By the way, under Mac there is an add-on which does exactly what I ask, it's MailTags for Mac os Mail.