[global-string] uses the highest privacy & security authentication available for your provider.
Some providers such as Gmail and Outlook, support OAuth, which means [global-string] will not have access to your username and password at all! Instead you will approve [global-string] as an application, and let it access your mail, as long as you like.
This process involves authorization directly with your provider (who already know your credentials: username and password) and we are given a token that you can control and revoke at any given time.
You can read about it here: http://techcrunch.com/2012/09/17/google-oauth-2-0-for-gmail-and-talk/.