Re: outlook.com windows phone sync (all folders)
This feature is enabled to prevent potentially unwanted data costs. However, if you choose "Sync this folder" for a sub-folder in your email folder, you won't need to sync it each time from that point onwards since that folder would then be automatically synchronized. As a logical proof, tapping on the three dots at the bottom of the screen within a synchronized sub-folder will show you the option to "don't sync this folder" - if you choose to stop synchronizing this folder at a latter point in time.