[Tfug] Conditional sorting in Mutt?

[Claude Rubinson]

I'm hoping that there might be a Mutt guru on the list.  By default,
Mutt threads based on the message id, falling back to the subject.
I'm wondering if it might be possible to configure threading based
upon a message's subject header.  That is to say, most of the time, I
like that Mutt will fall back to threading based upon the subject: for
example, it helps to keep TFUG threads together even when someone
sends email from a client that doesn't maintain the message id
header.  However, there are some specific instances this is counter
productive.  For example, emails that have generic headers such as
"Hi"  or "Re: Hey" get threaded together.  (The consequence is that
I'll sometimes miss emails with such headers.)

So, what I'd like to do is tell Mutt not to thread based upon the
subject for a regexp of particular subjects.  One way to do this would
be to, on opening an mbox folder, scan the subject headers and break
the thread for any message that matches the regexp, and then resort
the mailbox by it's default method.  But it's not clear to me that
Mutt can act on individual messages within a folder-hook.  Does anyone
know differently?  Or if there's a different way to accomplish the
desired behavior?

Thanks!

Claude