Rated 4 out of 5 stars

Installation und Betrieb sind nahezu selbst-erklärend.Ich hab mir meine Menue-Leiste etwas angepasst und kann jetzt problemlos eine Mail zeitversetzt versenden. Solange Thunderbird offen ist, funktioniert das spätere Senden wunderbar.

edith:
Installation an Usage are nearly self-explaning. I've changed the task bar for my needs an can delay mails without any problems. As long as Thunderbird is active the addon works perfectly.

@John: the fifth star is - in my opinion - reserved. There should be always a little , and in your case, a very little space to the 100% and five stars.

If I'd be able to give you 4.95 stars I'd did so. :)
(sry for my humble english)

This review is for a previous version of the add-on (4.1.4). 

Unless Google Translate is translating what you wrote incorrectly :-), it doesn't seem like you have anything negative to say about the add-on. So why four stars instead of five? What can I do to earn your fifth star? :-)