Thunderbird is including unrelated messages in threads

[kitesarefun]

Some time in the last month or couple of months Thunderbird suddenly started including unrelated messages in threads i.e. when View > Sort By > Threaded is checked. The messages in question don't have anything in common with the rest of the thread (subject, body etc.) except for recipients. Thunderbird never used to do this.

I wonder if maybe in an update Thunderbird's behavior was changed and now it recognizes if the sender clicked on "reply" (e.g. in order to send to a long list of recipients) and decides that this now counts as an actual reply to a threaded discussion *even though* the sender did *not* want this to happen and intentionally deleted everything in the message they replied to apart from the recipients.

Regardless of the source of the problem it's pretty much ruined the whole purpose of having threads because all my colleagues do what I just described pretty much every day (hitting Reply just to get all the addresses then deleting everything else in the email because they're starting a new topic).

[DanRaisch]

Thunderbird does not use message content (text) to determine which messages belong in a thread. See if this article is helpful -- https://github.com/protz/thunderbird-co ... -threading