Exactly what i was looking for! Rated 5 out of 5 stars

It's a fine new extension, but it needs still some adjustments. I found two of them, and I' sorry about posting this right here, but I'm kinda newbie here, and I just couldn't find where to report bugs.Well, here they are (Using TB 17):- If you have a "Answer To" address configured in one account, and then, composing, you do change to another sender account (in my case, the other account has no "Answer To" configured), the "Answer To" field remains the same.- If by composing, clicking on the "Gear" button and selecting more fields to show, those fields appear overlapping the compose window layout.Merci pour votre bon travail!
Michel, the overlapping issue is really, as you said, because of the Stationery extension installed.

This review is for a previous version of the add-on (1.0_r110). 

Thanks for your reply.I'll look at the first problem as soon as possible (before end of december).For the second problem, I suppose it's a conflict with another extension (IIRC, an early tester had this kind of problem when Stationery was installed). Please try to deactivate extensions and keep me informed. If you confirm that, unfortunately, I can do nothing.Michel

Update on 2013-03-05 : the version r116 handles your first problem (when an account has predefined emails for reply, cc or bcc)