I have been struggling to get it working, seems to be working properly now for new users.
However, there are some accounts I have used during testing it. I had to remove the mail configuration from the iPhone and add it back in.
But the old mail doesn't resync to the phone, only new mail.

I have configured the "Mail Days to Sync" to "No Limit".
I have removed the user from Data Synchronizer and added them back in.
Tried a "Reinitilize User" and "Resync Device", nothing works.
Doesn't matter if I switch between iPhone and iPad, just "fresh" mails.

I have a feeling the iPhone thinks they are local already, but because the account was deleted cannot show them...?

Is there a way to get it to work ok again (preferably without resetting iPad to factory defaults).