Test WordPress' is_email() and sanitize_email() functions

mailtest.php

<?php
// require wordpress
/**
 * @see http://en.wikipedia.org/wiki/Email_address
 */
$email   = array();
$email[] = 'john.smith(commentedemail)@example.com';
$email[] = '(commentedemail)john.smith@example.com';
$email[] = 'john.smith@(commentedemail)example.com';
$email[] = 'john.smith@example.com(commentedemail)';

$email[] = 'john.smith(commented email)@example.com';
$email[] = '(commented email)john.smith@example.com';
$email[] = 'john.smith@(commented email)example.com';
$email[] = 'john.smith@example.com(commented email)';

array_walk(
  $email,
	function($e){ printf('%s -> %s / %s<br>',$e, true==is_email($e)?'yes':'no', sanitize_email($e) ); }
);

/*
 * Output
 */
 
 /*
 john.smith(commentedemail)@example.com -> no / john.smithcommentedemail@example.com
(commentedemail)john.smith@example.com -> no / commentedemailjohn.smith@example.com
john.smith@(commentedemail)example.com -> no / john.smith@commentedemailexample.com
john.smith@example.com(commentedemail) -> no / john.smith@example.comcommentedemail
john.smith(commented email)@example.com -> no / john.smithcommentedemail@example.com
(commented email)john.smith@example.com -> no / commentedemailjohn.smith@example.com
john.smith@(commented email)example.com -> no / john.smith@commentedemailexample.com
john.smith@example.com(commented email) -> no / john.smith@example.comcommentedemail
*/