Old versions of Ubuntu used to save into a file in ~/.gnome2_private/ which stored base64 encrypted passwords (which was very insecure). If you're using a later version (which you probably are) then passwords are saved in a different way. The Gnome Keyring Manager now handles encrypted data on Ubuntu to provide a secure way of storing sensitive data.
To view your saved passwords, run the application "seahorse" which will open the password manager, double click the "Passwords: login" folder, and scroll down to your email account. Double click that and you can view your password for that account.
Easily view your saved passwords with Seahorse and Gnome Keyring
You'll also notice that browser passwords and some other keys are stored here too as it is used for all passwords.