On Sun, Nov 24, 2013 at 6:50 PM, Tim <ignored_mailbox(a)yahoo.com.au> wrote:
It doesn't require gmail to get messages threaded. Threading is
done by
the message headers, each message has its own message ID, each reply has
another header saying which message ID it's in reply to, and there's
another header listing all the message IDs that belong in the same
thread.
The last one (in-reply-to) is used by mail clients to group all
messages
in a thread together. The middle one (references) is used to thread
them all together in the right order.
Any mail client can do this. Any mail client can break this, and
some
do, by not not adding in-reply-to headers, and not adding and
maintaining the references header. When they do that, they bugger it up
for everyone else, as the data has been lost.
Message threading is NOT done by whatever text is written in the
subject
line. Though some broken clients think so. Some helpful clients will
try to use it, as well as threading headers, to fit in orphaned messages
into a thread (broken by other crappy clients), or to break apart a new
thread out of the middle of an existing one (when the subject line
changed). The latter not being a particularly good idea, either.
To see messages in their properly threaded order, one needs to use a
mail client that isn't broken in that regard (Evolution, Thunderbird,
and many others work), and pick the option that threads messages in the
message list window.
Conversely, one can unpick that option, and sort messages via some
other
criteria - such as by "date," making a mess of the order of messages
(hint - the generational order of which message came first, is done by
what's a reply to what, not the date that it was read or written, dates
are coincidental, not relational).
Thanks for taking time to explain this, I am re-reading to fully grasp it.