Rated 4 out of 5 stars

useful but the html added uses some color names (cyan, gold, etc.) : as a consequence my correspondents cannot see the hilite ( messaging clients or webmails ) except Lime, Yellow, Fuchsia , ... ---> should use instead something like <span style="background-color: rgb(255, 215, 0);"> except for the 16 colors of html4.1 ( https://www.w3.org/TR/html4/types.html#h-6.5 )

This review is for a previous version of the add-on (6.0.0). 

Dear gaido,
Thank you for this valuable hint!
I will start to work on the next version of my Add-on to improve this.

Update 13.05.2022:
Version 6.1.0 is now available and should eliminate this problem.