I'm looking to use ActiveSync to retrieve a given user's emails from newest to oldest. Unfortunately, when I make a sync request for all of a user's emails, by default ActiveSync starts with the oldest ones. This is a problem for users who have thousands of emails because they need to wait hours until their most recent emails are synced.
I considered using FilterTypes to first sync emails from 1 day ago, then 2 days ago, then 1 week ago, ... , 6 months ago, etc., but I am afraid this approach would be grossly inefficient because the same messages would end up getting synced many times.
Is there a way to sync emails that fall within a specific range? If so, I could sync emails from between 0 to 1 day ago, 1 to 2 days ago, 2 to 3 days ago, etc. without worrying about syncing the same emails.
AFAIK the FilterType approach is the only tool at your disposal. EAS (at least, the MS Exchange server implementation of it) will sync the items within your filtered range from oldest to newest.
Keep in mind that the problem of users having to wait hours for thousands of messages to come down should be a once-off. Once big folders have been synced, the subsequent sync conversations should be very efficient.