Rated 4 out of 5 stars

Very useful add-on. Please consider making the following improvements.

1) Do not use a space before a semicolon in the preferences. This is more minimalistic and is the convention in Thunderbird's GUI.

2) In preferences under the input field called "Spam detector:" add the help text "For SpamAssassin use X-Spam-Flag: YES" This will help users this add-on more quickly for SpamAssassin.

3) Add to preferences an option called "Short name on buttons" with a checkbox which is be default is unchecked. When checked, please use the following names on the buttons "Report spam" and "Report not spam". This will offer more serious buttons (without having to know what ham is) which also use less space in the GUI.

4) Align the Apply and Cancel buttons to the right in the preferences and use more verical space between the preferences and these buttons. This is looks less cramped and is the convention in Thunderbird's GUI.

5) Increase the thickness of the lines in the icon (of the add-on and the buttons) with the red arrow. This will make the arrow more visible and better blend in with the icons on the other buttons.

Looking forward to future releases of this add-on.