FEAT: Server-side THREAD and SORT

[andrinoff]

Is your feature request related to a problem?

Sorting/threading is done client-side, which is slow on large mailboxes.

Describe the solution you'd like

Use the IMAP SORT and THREAD extensions when the server advertises them.

Describe alternatives you've considered

Client-side sort/thread.

Additional context

See fetcher/search.go and backend/imap.

[floatpanebot]

Thanks for the suggestion!

If you want to see this feature land, give the original post a 👍. Maintainers prioritize feature requests by reaction count.
Comment to add detail or use cases — extra context helps triage.