Review for Thunderbird Conversations by IagoSRL
Rated 5 out of 5 stars
Very good extension! Give you full conversations messages, instead show you only messages per conversation included in the same folder (that is what Thunderbird does by default), and beautiful!
Only one thing: It needs compatibility with the Thunderbird per-folder option 'no-conversations', because now this option is discarted by the extension.
To create your own collections, you must have a Mozilla Add-ons account.