Comment 5 for bug 115153

I like to add two items to comment #4:

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).

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.

Note also that bug #20385 only implements the thread-by-date partially, since it
doesn't re-order the folder when new mail comes in. One either has scan the
whole folder to find the thread with the new message, or click again on
view->sort-by->date to force a "re-sort" of the folder; either solution is
cumbersome, this should be automatic.