Source: http://gizmodo.com/5552089/what-your-email-address-says-about-your-computer-skills
This chart justifies all your fears regarding Yahoo! and AOL users. And then some.
Reprinted with permission from Matthew Inman aka "The Oatmeal," a former web designer turned comic artist. You can see more of his work on The Oatmeal. Matthew is a one man operation, so be sure to check out posters and prints from his shop.
Oh, and Matthew wants you to know that if you enjoyed this comic, you might like the one about how to use semicolons as well: