It adds an item in the contextual menu when right-clicking on a message:
It adds also a menu with the forward button adding 'NotTo Forward'
Note that the NotTo/NotCc/NotBcc are not saved when message is saved as Draft.
Don't know how to do it! (IMHO it is impossible to do).
Currently, there are 3 types: NotTo/NotCc/NotBcc
With the addon option, you can limit to only one NotTo which applies to each type.
This extension has first been written by Tomer Rotstein (https://addons.mozilla.org/fr/thunderbird/addon/notto/).
It has been completely rewritten to work with TB 3.1.