If your client(s) handle the snoozing, copy "snoozed" messages to the "Snooze" folder (like "Draft", "Sent") - and check the date/time before copying it back to

If your client(s) handle the snoozing, copy "snoozed" messages to the "Snooze" folder (like "Draft", "Sent") - and check the date/time before copying it back to the "Inbox" as unread? If there's no meta-data readily availabile over IMAP (last modified...), maybe use "Snooze/deliver-at-1205-10102017" - a subfolder for each time slot?