Hi all, I found a way to delete multiple emails (sorry but doesn't work with text messages in the messages app) and this way also syncs you mailbox from watch to iphone and vice versa. first of all ensure all the mail on your iphone is up-to date and these are the emails you want to see on your watch. Then open mail app on watch, scroll to the bottom of all inboxes to find edit, tap edit and then untick the mailbox you want to sync and then the watch will either re-tick automatically or you have to tap to re-tick that mailbox. once this is done just come back out of that screen and check your inbox, it will now only show the emails currently in that said inbox as your iphone! Hope this helps