Rated 5 out of 5 stars

Thank you for an excellent product and prompt support replies. There is one longer-term problem with the plugin though: It seems to be forgetting or disselecting folders from some accounts (e.g. only 2 out of 3 Spam folders, only 1 out of 3 Sent Folders, respectively from 3 mail accounts). Not only it keeps disselecting them at every restart but also you need to unfold the grouped folders (+ sign) and then fold them again, to force the plugin to show all messages from all account.
Hint: This could be yet another conflict with the Exquilla plugin as I think it does it (mostly) with IMAP folders. But not 100% sure.

This review is for a previous version of the add-on (3.2.6).  This user has other reviews of this add-on.

Issues with folders being deselected are most likely to be Thunderbird or Exquilla. Conversations does very little with folders, except to do some initial changes.