After years of testing, Gmail has finally added a very useful security feature: tracking open sessions. If you log in to Gmail from more than one computer and you forget to sign out, you’ll be able to see the list of locations where your account can still be accessed.
Basic information is displayed as part of the page’s standard footer, and users looking for more detailed information can view a log that displays the most recent IP addresses to access the account, along with the type of access (Mobile, POP, etc.).
It’ll give you the idea on the most recent sessions including the access type and IP address. It’s not the end-all for email hijacking, but at the very least it’ll help you point-out intruders. And if you don’t see the feature yet, sit tight, Google is slowly rolling out the feature to all accounts.