Review for Quickfile by Lionel H. Grillet
Rated 4 out of 5 stars
When in the dialogue box to enter a folder abbreviation, do not use the mouse to select a folder. This just does not work. Use rather the tab or the arrows keys and then hit enter.
Apart from this bug, it is a superb add-on that spares lot of time, if you do archive your emails separately.
To create your own collections, you must have a Mozilla Add-ons account.