Review for MinimizeToTray by C. T.
Rated 4 out of 5 stars
Excellent add-on. One improvement would be to have the mail notification box automatically disappear whenever you click on an email listing and launch Thunderbird.
Currently, you have to separately close the notification box after launching Thunderbird. There is no need to have this additional step.
To create your own collections, you must have a Mozilla Add-ons account.