Rated 5 out of 5 stars

Great add-on. Just what I needed.
It works without any problem with TB24. To remember the settings for CC and BCC, just check the corresponding choices in the "fields appearance" tab in the MRC Compose Options in the Add-ons manager. It is true that changing these options in the compose window is not working even with TB24.1.0.

This review is for a previous version of the add-on (1.6). 

Glad you like it !
Changing options in the compose window is only temporary, just for the current window. The only way to have the options permanent is through the settings panel. It's not a bug, it's a feature ;-)