Review for Signature Switch by Larry Williams
Rated 4 out of 5 stars
I use this to change the signature based upon the recipient or mailing list, and it works as advertised. And since I think top-posting is a bad habit, this add-on helps me to break that habit.
The FAQ helped me understand how the add-on works and to resolve the line break issue.
To create your own collections, you must have a Mozilla Add-ons account.