Advanced Mail Validation

mailcheck_helper.php

<?php
/*
* Check if given mail is valid using:
*     filter_var()
*     check MX record
*     verify is user exist using telnet and SMPT session
*
*  I'm useing this helper in ajax respone so results are echo'ed as json
*/

// CONFIG
// you should have valid SPF record for your domain, if you don't have it, some host could reject your connection
define("HELO", 'yourhost.tld'); // define your host for HELO command
define("MAIL_FROM", '<you@yourhost.tld>'); // addres used for send command MAIL FROM:



if( !function_exists('mailcheck') )
{
	function mailcheck($email, $debug = FALSE)
	{
		if(!filter_var($email,  FILTER_VALIDATE_EMAIL))
		{
			$response['valid'] = FALSE;
			$response['error'] = 'syntax not valid against FILTER_VALIDATE_EMAIL';
		}
		else
		{
			$response['valid'] = TRUE;
			$response['error'] = '';
		}

		if($response['valid'] != FALSE)
		{
			$host = explode('@',$email);
			$dns = dns_get_record($host[1], DNS_MX);
			if(empty($dns))
			{
				$response['valid'] = FALSE;
				$response['error'] = 'no MX record for '.$host[1];
				return $response;
				exit;
			}

			$target   = $dns[0]['target'];
			$port     = 25;
			$errno    = "";
			$errstr   = "";
			$timeout  = 9;
			$newline  = "\r\n";
			$logArray = array();

			$connect = fsockopen($target, $port, $errno, $errstr, $timeout);
			$smtpResponse = fgets($connect, 4096);

			if(empty($connect)) {
				$response['valid'] = FALSE;
				$response['error'] = 'can\'t connect to '.$target;
				return $response;
				exit;
			}

			fputs($connect, "HELO ". HELO . $newline);
			$smtpResponse = fgets($connect, 4096);
			if($debug)
			{
				$response['debug'][] = "CMD: HELO ". HELO. " RESPONSE: " . preg_replace('/\s+/', ' ',$smtpResponse);
			}
			fputs($connect, "MAIL FROM: ". MAIL_FROM . $newline);
			$smtpResponse = fgets($connect, 4096);
			if($debug)
			{
				$response['debug'][] = "CMD: MAIL FROM: ". MAIL_FROM ." RESPONSE: ".preg_replace('/\s+/', ' ',$smtpResponse);
			}

			fputs($connect, "RCPT TO: <".$email.">" . $newline);
			$smtpResponse = fgets($connect, 4096);
			if($debug)
			{
				$response['debug'][] = "CMD: RCPT TO: <".$email."> RESPONSE: " .preg_replace('/\s+/', ' ',$smtpResponse);
			}

			if(strpos($smtpResponse, '250') === FALSE )
			{
				$response['valid'] = FALSE;
				$response['error'] = 'no such user';
				if($debug)
				{
					$response['debug'] = preg_replace('/\s+/', ' ',$smtpResponse);
				}

			}
			else
			{
				$response['valid'] = TRUE;
				$response['error'] = '';
				if($debug)
				{
					$response['debug'] = preg_replace('/\s+/', ' ',$smtpResponse);
				}

			}
		}

		return $response;
	}
}

header('Content-Type: application/json');
echo json_encode(mailcheck($_GET['mail'], TRUE));