[cthackers]

So what's wrong if you do a full validation (http://www.ex-parrot.com/pdw/Mail-RFC822-Address.html) ? You as developer or site owner or user don't need to do it by hand or in your head. It is done in a fraction of a second by the computer even if benefits are not the greatest like validating the strength of a password but still. Complaining about it because you don't like it and telling other people not to do it because of your reasons and spending time writing a blog post about it is overkill - like validating the email address with a regexp :)

[baudehlo]

There's nothing wrong with doing full validation. Just don't use that regexp - it's for RFC822 email addresses, which is how you might see them in an email header, including things like comments.

You want an RFC821 (or more specifically RFC5321 now) email address regexp. See my post here about the email validator I wrote: https://www.emailitin.com/email_validator