Bewertet mit 5 von 5 Sternen

[...]You can also include in the add-on options, e.g. the ability to disable the display of additional information, because not everyone analyzes spam in such detail.

Christian, You're absolutely right. I didn't think it through. :)
I have uploaded the screenshots to GitHub.

Diese Bewertung wurde für eine vorherige Version des Add-ons (1.2.0) abgegeben. 

Thanks for the positive feedback!

It would be really helpful if you could post a sample header of a mail where the scores were not recognised correctly in a new GitHub issue.
I haven't heard of the scrolling problem yet either. In this case, screenshots of the scrolling problem in another GitHub issue would also be great for solving the problem.
Regarding the add-on options and the possibility of hiding the additional information, I'm not quite sure what exactly should be hidden. The user has to actively press the button in a mail for this information to be displayed at all. I assume that the user then wants to see the actual details and not just the cryptic names of the rules and the score.