Review for SmartTemplates by Taavi
Rated 5 out of 5 stars
Indispensable add-on for every hardcore email user and for them who want their email look unique and have differently designed templates for different accounts. Very good functionality and many options for customization, especially the licensed version. Frankly, it should be TB core functionality!
And the author, Axel Grude, is an extremely helpful dude.
To create your own collections, you must have a Mozilla Add-ons account.