Review for Quick Folder Key Navigation by Dave Land
Rated 2 out of 5 stars
Terrible experience for first-time users. Documentation is mostly useless. Once I zeroed in on a folder, there was no way to "go back" to the full list in the main tab. I eventually just created a new Thunderbird window and re-created the additional tabs that I had open. Would not recommend until it has an "undo" or "restore" feature.
To create your own collections, you must have a Mozilla Add-ons account.