@PhL38F: SeaMonkey and Lightning Rated 5 out of 5 stars

SM 2.23 works with Lightning 2.8b1. For the current SM 2.24 you need Lightning 2.9b1.

You can find the corresponding Lightning downloads here:

https://addons.mozilla.org/en-US/thunderbird/addon/lightning/versions/?page=1

HTH

Greetings

Carsten

This review is for a previous version of the add-on (2.6.4).  This user has other reviews of this add-on.