That message is now threaded with the other chain causing some confusion and lost messages

I'm not sure how this can cause messages being lost.

Is there a way to break a message off of a thread and have it start it's own?

Don't reply to an existing message. Start with a new message instead.

That message is now threaded with the other chain causing some confusion and lost messages

I'm not sure how this can cause messages being lost.

Is there a way to break a message off of a thread and have it start it's own?

Don't reply to an existing message. Start with a new message instead.

Message is lost when I am looking for something that has a date of 2021 in the subject line and it nests with a message chain with 2020 in the subject line.

I plan to start a new chain in the future, knowing now that this is an issue, but my question was about breaking this message (and subsequent messages) off of this chain and into it's own as a new group of messages and away from the 2020 group

Here is some information on how to control threading:

http://kb.mozillazine.org/Stop_threading_by_subject

Here is some information on how to control threading: http://kb.mozillazine.org/Stop_threading_by_subject

So are you saying I should set "mail.strict_threading" to false to fix my issue?

Test the different settings to see which one works best. It may depend on how your correspondents' email programs handle threading.