Comment 6 for bug 115153

Sorting in a threaded view is, currently, almost always performed on the topmost
message in the thread. The one exception is Date, in which case the most recent
message is used to determine the thread's position.

It would probably be reasonably simple to use the same criterion for Order
Received sorting. That seems to be what reporter is seeking, and it makes as
much sense as the current sorting, so why not.

But adding a preference, let alone a checkbox, to control this makes little
sense.

Comment 4 and 5 expand on the original report far beyond what Reporter had to
say about this issue.

(In reply to comment #4)
> There seems to be a lot of misunderstanding about this bug.

If you had opened this bug, you would be justified in making that statement.

> 1) Closed threads should display the date of the latest message.

How do you display a thread view with some threads expanded and others
collapsed? The top message in the thread shows its own date for expanded
versions, and the latest date for collapsed versions? This is confusing, and I
would not like it.
Alternately, it would require a new column, "Latest Thread Date" or something.
This column would only be useful for threaded views and, in my opinion, would
take up far too much real-estate for very little gain.

> 2) Threads (closed and opened) should be sorted in the list by latest message
> date.

That's what happens now, if you sort Threads by Date.

> This should work for both received date (ala. SPAM) and sent date.

Well, first Received date needs be made available -- bug 166254, bug 216033. I
really don't see the point, myself; Order Received does the trick for locating
spam, and for anything else I can't see why the very infrequent misdated message
requires adding an entire new sort.

> This is a problem since when someone replies to a long-dormant thread, it is
> VERY difficult to find/see this mail message

But that has nothing to do with Received date, and it has nothing to do with
displayed date. If you sort your threads by date, and/or if you use
  View | Threads | Threads with Unread
it's fairly easy to locate the new stuff.

(In reply to comment #5)
> 3) when new messages arrive the mailbox threaded view should be reordered
> automatically so that old threads with new messages automatically jump to the
> end of the list (when sorting by date or order received).

This is bug 262319, and as I commented there, this would not be a good idea.
If I'm reading a message, I don't want the thread pane jumping around,
distracting me, as new messages arrive.

> 4) threading is not really a sort criterion but a way to present messages: it
> should therefore be an option that allows a user to choose between presenting
> messages individually or grouped/threaded. A mail folder can then be sorted on
> any of the date/sender/subject/... criteria, both in the threaded and in the
> unthreaded view.

This is exactly how Mozilla/TB behave now. Threading and sort criteria are
separate. It's true that, by default, clicking the Thread column header also
resorts by Order Received, and clicking any other header unthreads -- but this
behavior can be changed: see bug 219787.