Review for Mail Summaries by R. Menessec
Rated 5 out of 5 stars
Thought it conflicted with Thunderbird Conversations, but re-enabling it after an upgrade to TBird 12.0a has it working. Some sort of temporary glitch?
Excellent add-on!
If you're using Thunderbird 11.0 or higher, you'll need to download the latest beta of Conversations. The Conversations dev and I have coordinated on things so that nothing will break, provided you're on the right versions.
To create your own collections, you must have a Mozilla Add-ons account.