php email smpt validation error send of 34 bytes failed

Question

i want to validate email address is valid or not through smtp

I can't validate emails in codeigniter.

this is Error

fwrite(): send of 34 bytes failed with errno=10054 An existing connection was forcibly closed by the remote host.

This method check whether the email actually exist or not

i have got two same error in this code in different lines

function isValidEmail($email){
   $result=false;

   # BASIC CHECK FOR EMAIL PATTERN WITH REGULAR EXPRESSION
   if(!preg_match('/^[_A-z0-9-]+((\.|\+)[_A-z0-9-]+)*@[A-z0-9-]+(\.[A-z0-9-]+)*(\.[A-z]{2,4})$/',$email))
       return $result;

   # MX RECORD CHECK
     list($name, $domain)=explode('@',$email);

   if(!checkdnsrr($domain,'MX'))
      return $result;

   # SMTP QUERY CHECK
   $max_conn_time = 30;
   $sock='';
   $port = 25;
   $max_read_time = 5;
   $users=$name;

   # retrieve SMTP Server via MX query on domain
   $hosts = array();
   $mxweights = array();
   getmxrr($domain, $hosts, $mxweights);
   $mxs = array_combine($hosts, $mxweights);
   asort($mxs, SORT_NUMERIC);

   #last fallback is the original domain
   $mxs[$domain] = 100;
   $timeout = $max_conn_time / count($mxs);

   # try each host
   while(list($host) = each($mxs)) {
    #connect to SMTP server
    if($sock = fsockopen($host, $port, $errno, $errstr, (float) $timeout)){
      stream_set_timeout($sock, $max_read_time);
      break;
    }
   } 

   # did we get a TCP socket
   if($sock) {
      $reply = fread($sock, 2082);
      preg_match('/^([0-9]{3}) /ims', $reply, $matches);
      $code = isset($matches[1]) ? $matches[1] : '';

      if($code != '220') {
        # MTA gave an error...
        return $result;
      }

      # initiate smtp conversation
      $msg="HELO ".$domain;
      fwrite($sock, $msg."\r\n");
      $reply = fread($sock, 2082);

      # tell of sender
      $msg="MAIL FROM: <".$name.'@'.$domain.">";
      fwrite($sock, $msg."\r\n");
      $reply = fread($sock, 2082);


      #ask of recepient
      $msg="RCPT TO: <".$name.'@'.$domain.">";
      fwrite($sock, $msg."\r\n");
      $reply = fread($sock, 2082);

      #get code and msg from response
      preg_match('/^([0-9]{3}) /ims', $reply, $matches);
      $code = isset($matches[1]) ? $matches[1] : '';

      if($code == '250') {
        #you received 250 so the email address was accepted
        $result=true;
      }elseif($code == '451' || $code == '452') {
        #you received 451 so the email address was greylisted
        #_(or some temporary error occured on the MTA) - so assume is ok
        $result=true;
      }else{
        $result=false;
      }

      #quit smtp connection
      $msg="quit";
      fwrite($sock, $msg."\r\n");

      # close socket
      fclose($sock);

   }

   return $result;


}

$email='test1221s@gmail.com';

if(isValidEmail($email))
  echo "**** EMAIL EXISTS ****";
else
  echo "**** NOT A VALID EMAIL ****";

Answer 1

This method check whether the email actually exist or not

You can't do that, and the other side doesn't want to talk to you anymore because you tried.

In the past, crawlers would harvest email addresses by asking the server if user@domain.com exists. Then user1@domain.com. Then user2@domain.com, etc.

They would then end up with a list of valid users to spam.

Since then, mail servers have become much less open and "chatty" and won't respond to these queries and will in fact ban your address after a number of failures.

All you can do is send the actual email and handle the bounce if it's un-deliverable. If you insist on "checking" email addresses to see if they're good, you'll find that you soon have a blacklisted IP address.