Iphone 6 Manage storage

Does anyone know why under manage storage, the messages will always have "Messages (saved)" even when there are zero messages on my messages app? I deleted all of them and storage size didnt change.

Also, with Mail, I see I have mail and attachments accounting for 800 mb of storage. I assume there is a difference between imap and exchange accounts. Any info on which accounts are storing mail and attachments locally would help. Even if I toggle accounts as inactive the size doesn't seem to change.

Ihpone 6 16 MB

IOS 8.4

Cheers,