Which email service do you use and what services do you have running on her phone? If its gmail log into your account on computer and in the bottom right corner there's a 'Details' link. Click on it and window with current and short history of IP addresses will show up, along with a big 'Sign out all other web sessions' button you should click on. Then be sure to change your password. Facebook, Twitter and most other services have similar or equivalent ways usually buried in their 'Settings' menus to cancel any remote sessions, and of course be sure to then change your log in password.