http://ex-parrot.com/~pdw/Mail-RFC822-Address.html
http://fightingforalostcause.net/misc/2006/compare-email-regex.php
http://www.regular-expressions.info/email.html
http://haacked.com/archive/2007/08/21/i-knew-how-to-validate-an-email-address-until-i.aspx