Regular expression for validating email address

A simple regular expression (regex) for validating email address using PHP which I used mostly on my web apps.
I love being a Web developer and it’s been a lot of fun — this is one of them

<?php
function validateEmail($email) {
	if (ereg("^[_a-zA-Z0-9-]+(\.[_a-zA-Z0-9-]+)*@+([_a-zA-Z0-9-]+\.)*[a-zA-Z0-9-]{2,200}\.[a-zA-Z]{2,6}$", $email)) {
		return true;
	} else {
		return false;
	}
}
?>

Usage:

<?php
if (validateEmail($email)) {
	// Email address is valid, do your process here...
} else {
	// Email address is not valid, do your process here...
}
?>