Lawrence Greenfield <leg+(_at_)andrew(_dot_)cmu(_dot_)edu>
And fetching the envelope structure (or ALL) is so much faster than even
(ALL BODY[HEADER.FIELDS (REFERENCES)])
Actually, plenty of IMAP servers (such as the Cyrus-derived ones) will
return References with approximately the same speed as ENVELOPE
information, since this information is cached in the same place.
But more bandwidth use, which can be a problem. From next week, I'll be in
a place where pigeon-carried IP might be an improvement and expect to care
deeply about bandwidth.
Anyway, I've had luck with fetching only some references fields. The
algorithm goes something like this (rather simplified):
1. Fetch the subjects.
2. Group the message roughly by subject.
3. For each subject group with at least one unthreaded message:
a. Fetch the references field for the highest-numbered unthreaded
message in that group.
b. Use that to thread as many messages as possible.
It becomes a little more complex in reality, particularly if you want to
avoid round-trips, but the concept is fairly simple, and the algorithm
generally doesn't need to fetch very many references fields in order to
make sense of a thread.
--Arnt (doesn't think much of thread=references)