Server-side threading

[ohw.giles at gmail.com]

Hi list,

Considering a message A in INBOX, where a reply B is sent and copied to
the recipient's SENT folder, and to which a reply-to-reply C is 
received,
again in INBOX, how should the list of threads in INBOX be (ideally)
retrieved?

Using THREADS=REFS when listing threads in INBOX to avoid matching
unrelated threads unfortunately seems to miss the above example because 
B
is only in SENT, not INBOX. REFERENCES allows A to be linked to C, but
the sent message is missing from the returned thread. Of course this is
by design.

When listing messages in a selected mailbox, many modern clients provide
the experience of listing the messages grouped by thread, showing all
threads where *at least one message in the thread is in the selected
mailbox*. IIUC, clients usually build their own indexes to achieve this,
which seems wasteful.

Does dovecot provide a server-side way to list or search messages and
return threaded results in this manner?