I originally had problems with Mail app: delete and re-add your email accounts (have your PWs handy). This is what a Tier 2 advisor at

Using an early 2011 MBP 13” with a maximum of 8 GBs RAM installed.

Try ‘desk connect’ app for iOS and OS X devices. Works both ways and keeps files on iDevice for up to 30 days.

Check out ‘desk connect’ app for OS X and iOS.