[jstedfast]

> I can show you, right now, a 500,000 message view across multiple folders infinite scrolling with JMAP and I can jump to the middle of that view and load a screenful of messages. You CAN NOT do an IMAP sort without fetching one record for every message in the folder. If you have a million messages in a folder (yes, we have customers who do that) then you need to fetch a million records.

If I've got the sort order (from a UID SORT REVERSE DATE command), and a user jumps to the middle of the list, I can FETCH just the visible subset of messages by calculating what the UIDs would be and then doing:

TAG UID FETCH <visible-uid-set> (ENVELOPE FLAGS ...)

I'm not sure why you think you'd have to issue a FETCH command for each message individually.

[brongondwana]

Yeh, no shit - but you need to either have downloaded EVERY UID in that sort order (no updates either - if ANYTHING changes in the folder while you were disconnected you need to re-fetch the entire sort list) or you need sort extensions which don't even exist yet.

[jstedfast]

Then why did you say you couldn't if "yea, no shit" you knew you could?

If you've already grabbed ENVELOPE info for all of the older messages (i.e. all of the messages from a previous session), you can just download the ENVELOPE info of new messages and then sort locally.

I mean, if only a few messages have arrived since the previous session, it's probably faster to grab the ENVELOPEs and then sort locally.

If there's a lot of new mail, it might be more efficient to sort server side and just fetch the ENVELOPEs for the messages in view and lazy-load the rest when the user is idle (which is most of the time).

A dead-simple heuristic would be if the number of new messages is fewer than the number of messages you can show in a list, then it's probably not worth doing server-side sorting, right? Does that make sense? Especially as mobile devices get more and more powerful. You just need to design your sqlite database such that it's setup to do optimal sorting by whatever sorting method you are using (by date should be easy, right?).

I've actually done this sort of thing before (although not with IMAP), so I know it's doable. It just takes thought to design it and time to implement it.

I've studied the IMAP specs in my spare time over the past year or so and know them pretty well and I'm confident I could get good results if I had the time to implement it, but it's not like anyone in the world could implement a solid IMAP client in a week or even a month working on it full time and seeing as how I couldn't spend full-time working on writing a mail client due to the fact that I have a job that doesn't involve me writing said mail client, I don't see how you could possibly expect me to implement one in a month.