Disable AOL from starting up automatically. Create a shortcut from your desktop with a location of "mailto:" without the quotes. Name the shortcut anything you like and when you are finished it should automatically acquire the blue AOL icon. (Exit AOL if you are signed in and test the shortcut. It should automatically sign you in but it will automatically open your email window as well.)
If you are happy with it, right click your Start button, click on Open All Users. Open the Programs Folder and drag your new shortcut into the Startup folder.