I'm subscribed to some mailing lists and every day people reply to a wrong mail (or they don't reply at all), so that their mail lands in the wrong (or a new) thread.
I set the mail display in "View → Sort by" to "Threaded".
Example: mailing list "Foobar":
[Foobar] random topic Re: [Foobar] random topic Re: [Foobar] random topic Re: [Foobar] random topic Re: [Foobar] random topic [Foobar] I'm John Doe Re: [Foobar] I'm John Doe Re: [Foobar] Welcome, John Re: [Foobar] random topic
There are two discussions, one about "random topic", one about "John Doe". The subject line changes in the discussion about John Doe, which is fine (no problem here). But the last mail should be pigeonholed in the first thread. Instead it is at the top-level.
Now, how can I move that last mail into the correct thread? I tried to drag&drop it at the mail I think it should be a reply to, but this doesn't work.
I think theoretically it should be possible by fiddling with the mail headers after receiving the mail, but this doesn't seem to be a comfortable way.
Whatever the solution might be, it should not work locally only. Instead, it should be saved on the mail (headers), so that all IMAP clients get the manually updated order. So, if it would be possible with some other FLOSS tool instead of Thunderbird, I am fine with it, because the correct mail sorting would be applied to the mails displayed in Thunderbird, too.