This post from Hunch Blog is overall very true.
We do stereotype people by their email addresses.
Example A – see a ’69′ at the end of a sentence, and yes, you do roll your eyes.
Example B – you think that purposely misspelled words are juvenile.
Whilst the data probably isn’t going to make it into a PHD thesis, I did find it generally true. And the pictures and commentary made it a great read as well.