Rated 2 out of 5 stars

For me, it works only with emails I answer within thunderbird. The Emails that I answer from my android phone using the gmail app are not included in the threads. In this sense, I cannot rely on it that I always see the entire conversation!

Hi, unfortunately this sounds like an issue with Thunderbird itself, rather than with Conversations.

The Conversations add-on relies on Thunderbird to provide the threading/conversation information, so if it isn't working it is most likely a Thunderbird issue.

I suspect in this case, Thunderbird hasn't "seen" the emails in the sent folder that Android has added, and therefore hasn't indexed them.

I suggest you file a bug at https://bugzilla.mozilla.org/ and report it to the team. Hopefully they can solve it.