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?