<?

if(!function_exists('checkEmail')){

// Email validation function
function checkEmail($emailaddress, $checkdomain = 0)
{
	// trim leading and trailing whitespace
	$emailaddress = trim($emailaddress);
	// if root terminator present, remove it
	if(substr($emailaddress, strlen($emailaddress) -1) == '.'){
		$emailaddress = substr($emailaddress, 0, strlen($emailaddress) - 1);
	}
	
	// check for any character not in the ascii-7 character set, plus control charaters
	if(preg_match('/[^\040-\176]/', $emailaddress)){
		// short-circuit if any control characters or non-ascii-7 characters are found
		return false;
	}
	
	// regular expressions
	$mailpartpattern = "/^([^\@]+)\@([^\@]+)$/";
	$mbox = '^\s\.<>\(\),;:\"\[\]\@';
	$mailboxpattern = '/^[' . $mbox . ']+(\.?[' . $mbox . ']+)*$/';
	$dom = "a-z0-9";
	$root = "a-z";
	$labelpattern = '/^[' . $dom . ']+(-[' . $dom . ']+)*$/i';
	$rootpattern = '/^[' . $root . '][' . $root . ']+$/i';
	//$pattern = '/^([' . $mbox . ']+(\.?[' . $mbox . ']+)*)\@([' . $dom . ']+([.-]?[' . $dom . ']+)*\.[' . $root . ']{2,4})$/i';

	if(preg_match($mailpartpattern, $emailaddress, $mailparts))
	{
		$mailbox = $mailparts[1];
		$domain = $mailparts[2];
		// match the mailbox portion against the regex
		if(! preg_match($mailboxpattern, $mailbox)){
			return false;
		}
		
		// OK, now, the domain cannot exceed 255 chars
		if(strlen($domain) > 255) return false;
		
		// Break the domain portion into "labels" on the dots.
		$labels = explode('.', $domain);
		for($idx = 0; $idx < count($labels) -1; $idx ++){
			// no null labels
			if(strlen($labels[$idx]) == 0) return false;
			// labels may not exceed 63 chars
			if(strlen($labels[$idx]) > 63) return false;
			// check that the label is valid
			if(! preg_match($labelpattern, $labels[$idx])) return false;
		}
		// check the TLD
		if(! preg_match($rootpattern, $labels[count($labels) - 1])) return false;
		
		// note, terminated domains with . to prevent 
		// local domain wildcards from playing havoc.
		if($checkdomain)
		{
			if(! checkdnsrr($domain . '.', "MX")){
				if(! checkdnsrr($domain . '.', "ANY"))
					return false;
			}
		}
		return true;
	}
	else return false;
}

}
?>