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 :)