I'd recommend everyone standardize on the HTML5 email validation spec, which differs from RFC822 by disallowing several very seldom-used features of email addresses (like comments!), but can be recognized by regexes.
Here's the section on email validation in the HTML5 spec:
http://www.whatwg.org/specs/web-apps/current-work/multipage/states-of-the-type-attribute.html#e-mail-state-%28type=email%29
And this is the regex:
^[a-zA-Z0-9.!#$%&'*+/=?^_`{|}~-]+@[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,253}[a-zA-Z0-9])?(?:\.[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,253}[a-zA-Z0-9])?)*$