Rated 5 out of 5 stars
Marvelous add-on, works perfect and saves a lot of trouble.
Only one issue/recommendation: In "replies" or "forwards", the signature is always put at the end. There is no way (at least I wasn't able to figure out) to insert the signature after a reply or at cursor position.
Changing the Account Settings-Composition-Addressing don't have any effect.
With this feature, I would give 6 stars.