Rated 5 out of 5 stars
If the Mozilla developers had any brains and actually used their software, they would incorporate this add-on into every version of Thunderbird as a default function. Sadly they are clueless and still haven't caught on, even on version 13.0
I don't know how people use Thunderbird without this add-on, minimizing to tray is the ONLY option as far as I am concerned when it comes to an email desktop program. No accidental closing, less clutter on the main task bar, and you still get all the notifications from the tray and can manually/force retrieve your emails if you want with a simple right-click command from the tray!
Even the new Minimize to Tray: Revived is very flawed and doesn't work nearly as well as this add-on does, which is a shame as this add-on is only good to Thunderbird 2.0... which has many vulnerabilities now.
I hope this developer re-creates this add-on for the later versions of Thunderbird, because it might just be the best, simplest, and most practical add-on I have ever seen in the entire Mozilla lineup.
Flawless would be an understatement. I have never had any problems with this add-on, and it has always worked without fail. From the very beginning it has done everything I ever wanted it to.