getmxrr

(PHP 4, PHP 5, PHP 7, PHP 8)

getmxrr — Ottiene i record MX corrispondenti a un dato nome di host Internet

Descrizione

getmxrr(string $hostname, array $mxhosts, array $weight = ?): int

Cerca nel DNS i record MX corrispondenti a hostname. Restituisce true se ne vengono trovati. Restituisce false se non ne vengono trovati o se avviene un errore.

La lista di record MX trovati viene messa nell'array mxhosts. Se viene indicato l'array weight, esso viene riempito con le informazioni ottenute sui vari pesi.

Vedere anche checkdnsrr(), gethostbyname(), gethostbynamel(), gethostbyaddr()e la pagina man named(8).

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User Contributed Notes 19 notes

down

Robert Imhoff ¶

13 years ago

I tried using getmxrr() to validate the domain portion of email addresses in enquiry submission forms, and there is a curious effect with some top-level domains when checking non-existant domains.

With sdlkfjsdl.com, since the domain does not exist, getmxrr() returns false, as expected, and the returned mxhosts array is empty.

But with sdlkfjsdl.gov, getmxrr() returns true,  and the returned mxhosts array contains one element: NULL

With sdlkfjsdl.org, getmxrr() returns true,  and the returned mxhosts array contains one element: '0.0.0.0'

With sdlkfjsdl.co.uk, getmxrr()  returns true and supplies one MX record: uk-net-wildcard-null-mx.centralnic.net

So to validate the email domain, it would seem one has to check the returned mxhosts array to exclude the possibility of mxhosts being returned as NULL, 0.0.0.0 and wildcard ...

down

Jay ¶

17 years ago

As stated, some of the code listed below will have trouble with multiple equal weights, such as if you query gmail.com. The following code will prevent that by switching the key/values.

<?php

// Get the records
getmxrr("gmail.com", $mx_records, $mx_weight);

// Put the records together in a array we can sort
for($i=0;$i<count($mx_records);$i++){
    $mxs[$mx_records[$i]] = $mx_weight[$i];
}

// Sort them
asort ($mxs);

// Since the keys actually hold the data we want, just put those in an array, called records     
$records = array_keys($mxs);

// Simply echoes all the stuff in the records array     
for($i = 0; $i < count($records); $i++){
    echo $records[$i];
    echo '<br>';
}

?>

If you wanted to get the weight, you would use "array_values($mxs);" instead of "array_keys($mxs);".

Hope this helps some people.

down

rune dot heggtveit at devzone dot progative dot com ¶

19 years ago

An other way to do mx-lookup on a windows platform.
Rewrote this from an other class i wrote for DNS lookup - so it might be a bit messy - but hope you get the idea.

Big thanks to the rfc community.

<?php

class mxlookup
{
      var $dns_socket = NULL;
      var $QNAME = "";
      var $dns_packet= NULL;
      var $ANCOUNT = 0;
      var $cIx = 0;
      var $dns_repl_domain;
      var $arrMX = array();

      function mxlookup($domain, $dns="192.168.2.1")
      {
         $this->QNAME($domain);
         $this->pack_dns_packet();
         $dns_socket = fsockopen("udp://$dns", 53);

         fwrite($dns_socket,$this->dns_packet,strlen($this->dns_packet));
         $this->dns_reply  = fread($dns_socket,1);
         $bytes = stream_get_meta_data($dns_socket);
         $this->dns_reply .= fread($dns_socket,$bytes['unread_bytes']);
         fclose($dns_socket);
         $this->cIx=6;
         $this->ANCOUNT   = $this->gord(2);
         $this->cIx+=4;
         $this->parse_data($this->dns_repl_domain);
         $this->cIx+=7;

         for($ic=1;$ic<=$this->ANCOUNT;$ic++)
         {
           $QTYPE = ord($this->gdi($this->cIx));
           if($QTYPE!==15){print("[MX Record not returned]"); die();}
           $this->cIx+=9;
           $mxPref = ord($this->gdi($this->cIx));
           $this->parse_data($curmx);
           $this->arrMX[] = array("MX_Pref" => $mxPref, "MX" => $curmx);
           $this->cIx+=3;
         }
      }

      function parse_data(&$retval)
      {
        $arName = array();
        $byte = ord($this->gdi($this->cIx));
        while($byte!==0)
        {
          if($byte==192) //compressed
          {
            $tmpIx = $this->cIx;
            $this->cIx = ord($this->gdi($cIx));
            $tmpName = $retval;
            $this->parse_data($tmpName);
            $retval=$retval.".".$tmpName;
            $this->cIx = $tmpIx+1;
            return;
          }
          $retval="";
          $bCount = $byte;
          for($b=0;$b<$bCount;$b++)
          {
            $retval .= $this->gdi($this->cIx);
          }
          $arName[]=$retval;
         $byte = ord($this->gdi($this->cIx));
       }
       $retval=join(".",$arName);
     }

     function gdi(&$cIx,$bytes=1)
     {
       $this->cIx++;
       return(substr($this->dns_reply, $this->cIx-1, $bytes));
     }

      function QNAME($domain)
      {
        $dot_pos = 0; $temp = "";
        while($dot_pos=strpos($domain,"."))
        {
          $temp   = substr($domain,0,$dot_pos);
          $domain = substr($domain,$dot_pos+1);
          $this->QNAME .= chr(strlen($temp)).$temp;
        }
        $this->QNAME .= chr(strlen($domain)).$domain.chr(0);
      }

      function gord($ln=1)
      {
        $reply="";
        for($i=0;$i<$ln;$i++){
         $reply.=ord(substr($this->dns_reply,$this->cIx,1));
         $this->cIx++;
         }

        return $reply;
      }

      function pack_dns_packet()
      {
        $this->dns_packet = chr(0).chr(1).
                            chr(1).chr(0).
                            chr(0).chr(1).
                            chr(0).chr(0).
                            chr(0).chr(0).
                            chr(0).chr(0).
                            $this->QNAME.
                            chr(0).chr(15).
                            chr(0).chr(1);
      }

}

?>

<?php

/* Exampe of use: */
$mx = new mxlookup("php.net");

print $mx->ANCOUNT." MX Records\n";
print "Records returned for ".$mx->dns_repl_domain.":\n<pre>";
print_r($mx->arrMX);

?>

Return:

02 MX Records Records returned for php.net:

Array
(
    [0] => Array
        (
            [MX_Pref] => 15
            [MX] => smtp.osuosl.org
        )

    [1] => Array
        (
            [MX_Pref] => 5
            [MX] => osu1.php.net
        )

)

down

zorlac_man at hotmail dot com ¶

20 years ago

For some reason this and the other DNS lookup functions seem to be really slow on my Linux box. I've checked several things and have no explanation.

As a work-around, I gave in and just used a system call to dig:

<?php
CheckMX("fakedomain.org");
CheckMX("hotmail.com");

function CheckMX($domain) {
        exec("dig +short MX " . escapeshellarg($domain),$ips);
        if($ips[0] == "") {
                print "MX record found for $domain not found!\n";
                return FALSE;
        }
        print "MX Record for $domain found\n";
        return TRUE;
}
?>

Output:

MX record found for fakedomain.org not found!
MX Record for hotmail.com found

As someone else pointed out, it is prudent to check to see if the TLD has an IP address if the MX record is not found.

down

php [spat] hm2k.org ¶

15 years ago

I decided to have a bash at this after doing a bit of research...

<?php

// getmxrr() support for Windows by HM2K <php [spat] hm2k.org>
function win_getmxrr($hostname, &$mxhosts, &$mxweight=false) {
    if (strtoupper(substr(PHP_OS, 0, 3)) != 'WIN') return;
    if (!is_array ($mxhosts) ) $mxhosts = array();
    if (empty($hostname)) return;
    $exec='nslookup -type=MX '.escapeshellarg($hostname);
    @exec($exec, $output);
    if (empty($output)) return;
    $i=-1;
    foreach ($output as $line) {
        $i++;
        if (preg_match("/^$hostname\tMX preference = ([0-9]+), mail exchanger = (.+)$/i", $line, $parts)) {
          $mxweight[$i] = trim($parts[1]);
          $mxhosts[$i] = trim($parts[2]);
        }
        if (preg_match('/responsible mail addr = (.+)$/i', $line, $parts)) {
          $mxweight[$i] = $i;
          $mxhosts[$i] = trim($parts[1]);
        }
    }
    return ($i!=-1);
}

// Define
if (!function_exists('getmxrr')) {
    function getmxrr($hostname, &$mxhosts, &$mxweight=false) {
        return win_getmxrr($hostname, $mxhosts, $mxweight);
    }
}

/* example */

$domain='php.net';
echo "<pre>";
getmxrr($domain,$mxhosts,$mxweight);
print_r($mxhosts);
print_r($mxweight);

?>

down

Anonymous ¶

8 years ago

One small polyfill for the getmxrr function(even when it's missing from linux system)

function getmxrr($hostname, &$mxhosts, array &$mxweight=null)
                {
                   $mxhosts = array();
                   exec('nslookup -type=mx '.$hostname, $result_arr);
                   foreach($result_arr as $line) 
                    {
                        if (preg_match("/.*mail exchanger = (.*)/", $line, $matches)) 
                        {  
                            $s_xo=explode(' ', $matches[1]);
                            $mxhosts[] = $s_xo[1];
                            $mxweight[] = $s_xo[0];                            
                        }                     
                    }
                   return( count($mxhosts) > 0 );
                }

down

geoffbrisbine A T y a h o o DOT c o m ¶

22 years ago

I was pretty disappointed that the Win32 build of PHP doesn't incorporate getmxrr so, since I'm a naive newbie, I decided to hack together my own (and I stress hack).  This has been tested on Win 2000 and Win XP.  There's no reason this shouldn't work on Win NT but it will not work on Win 9x (you need the nslookup command).  It will finish with the array $mx that will be a multidimensional array with the MX preference, host name and ip address. You can do a print_r ( $mx ) to see what it looks like.

-----------------------------------------------

<?php
$command = "nslookup -type=mx yahoo.com";
exec ( $command, $result );
    
$i = 0;
while ( list ( $key, $value ) = each ( $result ) ) {
    if ( strstr ( $value, "mail exchanger" ) ) { $nslookup[$i] = $value; $i++; }
}
    
while ( list ( $key, $value ) = each ( $nslookup ) ) {
    $temp = explode ( " ", $value );
    $mx[$key][0] = $temp[3];
    $mx[$key][1] = $temp[7];
    $mx[$key][2] = gethostbyname ( $temp[7] );
}

    array_multisort ( $mx );
?>

down

tomhutter at web dot de ¶

18 years ago

Leonardt's code fails with multiple mx records with the same wight. You can easily change this by switching keys and values in the mxs array:

     for($i=0;$i<count($mx_records);$i++){
       $mxs[$mx_records[$i]] = $mx_weight[$i];
     }

     arsort ($mxs );
     reset ($mxs);

    while (list ($mx_host, $mx_weight) = each ($mxs) ) {

cheers 

Tom

down

php dot net at oitc dot com ¶

18 years ago

This function has some strange side effects when dealing with aliases...

My function:

        if (getmxrr($fqdn, $mx_records, $mx_weight)) {
            // copy mx records and weight into array $mxs
            // ignore multiple mx's at the same weight
            for ($i = 0; $i < count($mx_records); $i++) {
                $mxs[$mx_weight[$i]] = $mx_records[$i];
            }
            // sort array mxs to get servers with highest priority
            ksort ($mxs, SORT_NUMERIC);
            reset ($mxs);
        } else {
            // No MX so use A
            $mxs[0]= $fqdn;
        }

fails because a $fqdn containing an alias returns a true yet on return both $mx_records and $mx_weight contain nothing!

The solution until this gets fixed is to replace if (getmxrr($fqdn, $mx_records, $mx_weight)) with

        // Handle aliases etc.
        if ($result = getmxrr($fqdn, $mx_records, $mx_weight)) {
            if(!isset($mx_records) || (count($mx_records) == 0)) $result = false;
        }
        // Process MXs
        if ($result) {

Hope this helps others....  Tom

down

MagicalTux at ooKoo dot org ¶

18 years ago

If you want to use getmxrr on windows, be careful as choward AT fast DOT net DOT NO SPAM PLZ's function has a security flaw.

It passes its argument to an external command without escaping it. If you don't validate the input, someone may manage to run nasty things on your system.

Here's a fixed version (just added escapeshellarg())

<?php
function getmxrr($hostname, &$mxhosts)
{
    $mxhosts = array();
    exec('%SYSTEMDIRECTORY%\\nslookup.exe -q=mx '.escapeshellarg($hostname), $result_arr);
    foreach($result_arr as $line)
    {
      if (preg_match("/.*mail exchanger = (.*)/", $line, $matches))
          $mxhosts[] = $matches[1];
    }
    return( count($mxhosts) > 0 );
}//--End of workaround

//test..
getmxrr('yahoo.com', $mxhosts);
print_r($mxhosts);
?>

This way you'll avoid a lot of nasty things ;)

down

off at NOSPAM dot abwesend dot de ¶

18 years ago

Concerning the message by 'rolf at rowi dot net' (do a check on a address containing a subdomain) we could use:

$email = 'abc@etpc01.trier.fh-rpl.de';
            
$strDot      = '.';
$strAfterAt  = substr(strstr($email, '@'), 1);
$chunks      = explode($strDot, $strAfterAt);
$cntChunks   = count($chunks) - 1;

$strDomain = $chunks[($cntChunks-1)] . $strDot . $chunks[$cntChunks];

if (!getmxrr( $strDomain, $mxhosts )) {
    echo 'Mailserver not found';
}

// $strDomain is set to 'fh-rpl.de';

down

richard dot quadling at bandvulc dot co dot uk ¶

19 years ago

Windows alternative for getmxrr without the need for PEAR.



<?php

define('DEFAULT_GATEWAY', 'nnn.nnn.nnn.nnn');

if (!function_exists('getmxrr'))

    {

    /*

        This function is a replacement for the missing Windows function getmxrr.

        

        The parameters are the same as those for the normal getmxrr function.

        

        The steps this function takes are :

        

        1 - Use NSLOOKUP.EXE to get the MX records for the supplied Host.

        2 - Use regular expressions to extract the mail servers and the preference.

        3 - Sort the results by preference.

        4 - Set the return arrays.

        5 - Return true or false.

    */

    function getmxrr($s_HostName, array &$a_MXHosts = NULL, array &$a_Weights = NULL)

        {

        // Simulate all the required network activity by executing windows' NSLOOKUP.

        $s_NSLookup = shell_exec("nslookup -q=mx {$s_HostName} 2>nul");

        preg_match_all("'^.*MX preference = (\d{1,10}), mail exchanger = (.*)$'simU", $s_NSLookup, $a_MXMatches);



        // If there is something to return ...

        if (count($a_MXMatches[2]) > 0)

            {

            // Produce output arrays if they have been requested.

            $i_ArgCount = func_num_args();

            if ($i_ArgCount > 1)

                {

                array_multisort($a_MXMatches[1], $a_MXMatches[2]);

                switch ($i_ArgCount)

                    {

                    case 3 :

                        $a_Weights = $a_MXMatches[1];

                    case 2 :

                        $a_MXHosts = $a_MXMatches[2];

                    }

                }

            return True;

            }

        else

            {

            return False;

            }

        }

    }

?>



You will need to know your default gateway (either it's IP address or its name).



To do this, run the program IPCONFIG /ALL at a cmd prompt and look for the Default Gateway.



Then replace the 'nnn.nnn.nnn.nnn' with the address.



Richard.

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-1

siclawrence at gmail dot com ¶

19 years ago

This code replicates online tools that let you check if an email address is valid. First it checks if the email format is correct, then looks up and prints the mx records. All nicely formatted with fancy words that in the end prints whether the email address valid or invalid.

<?php
$email = "email@domain.com";

print("Checking: $email<br>");

if (eregi("^[_a-z0-9-]+(\.[_a-z0-9-]+)*@[a-z0-9-]+(\.[a-z0-9-]+)+$", $email)) {

    print("Format Test: PASSED<br>");
    print("Online host verification Test...<br><br>");
    print("MX Records for: $email<br>");
    
    list($alias, $domain) = split("@", $email); 
    
    if (checkdnsrr($domain, "MX")) {
    
        getmxrr($domain, $mxhosts);
        
        foreach($mxhosts as $mxKey => $mxValue){
            print("&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;$mxValue<br>");
        }
        
        print("Online host verification Test: PASSED<br><br>");
        print("Email Status: VALID");
    
    } else {
    
        print("&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;No records found.<br>");
        print("Online host verification Test: FAILED<br><br>");
        print("Email Status: INVALID");
    
    }

} else {

    print("Format Test: FAILED<br><br>");
    print("Invalid email address provided.<br><br>");
    print("Email Status: INVALID");
    
}
?>

down

-1

ng4rrjanbiah at rediffmail dot com ¶

20 years ago

Here is a better workaround for Windows platform. Tested on Windows XP. Highly impressed by "geoffbrisbine A T y a h o o DOT c o m"'s idea of nslookup usage.

<?php
function getmxrr($hostname, &$mxhosts)
{
   $mxhosts = array();
   exec('nslookup -type=mx '.$hostname, $result_arr);
   foreach($result_arr as $line) 
    {
      if (preg_match("/.*mail exchanger = (.*)/", $line, $matches)) 
          $mxhosts[] = $matches[1];
    }
   return( count($mxhosts) > 0 );
}//--End of workaround

//test..
echo getmxrr('yahoo.com', $mxhosts);
print_r($mxhosts);
?>

HTH,
R. Rajesh Jeba Anbiah

down

-1

paul at start dot co dot uk ¶

23 years ago

Prevent your dns server from 'creating' a valid host name by appending the local domain to incomplete emails by appending to the domain a  trailing . both in the pattern match and mx checks:



<?php

if (eregi("^[0-9a-z_]([-_.]?[0-9a-z])*@[0-9a-z][-.0-9a-z]*\\.[a-z]{2,3}[.]?$", $string, $check)) { 

    $host = substr(strstr($check[0], '@'), 1)."."; 

    if ( getmxrr($host, $validate_email_temp) ) 

        return TRUE; 

    // THIS WILL CATCH DNSs THAT ARE NOT MX. 

    if(checkdnsrr($host,"ANY"))

        return TRUE; 

}

?>

down

-1

Lennart Poot(www.twing.nl) ¶

18 years ago

This script validates an e-mail adress using getmxrr and fsockopen

1. it validates the syntax of the address.
2. get MX records by hostname
3. connect mail server and verify mailbox(using smtp command RCTP TO:<email>)

When the function "validate_email([email])" fails connecting the mail server with the highest priority in the MX record it will continue with the second mail server and so on..

The function "validate_email([email])" returns 0 when it failes one the 3 steps above, it will return 1 otherwise

Grtz Lennart Poot

<?
function validate_email($email){
   $mailparts=explode("@",$email);
   $hostname = $mailparts[1];

   // validate email address syntax
   $exp = "^[a-z\'0-9]+([._-][a-z\'0-9]+)*@([a-z0-9]+([._-][a-z0-9]+))+$";
   $b_valid_syntax=eregi($exp, $email);

   // get mx addresses by getmxrr
   $b_mx_avail=getmxrr( $hostname, $mx_records, $mx_weight );
   $b_server_found=0;

   if($b_valid_syntax && $b_mx_avail){
     // copy mx records and weight into array $mxs
     $mxs=array();

     for($i=0;$i<count($mx_records);$i++){
       $mxs[$mx_weight[$i]]=$mx_records[$i];
     }

     // sort array mxs to get servers with highest prio
     ksort ($mxs, SORT_NUMERIC );
     reset ($mxs);

     while (list ($mx_weight, $mx_host) = each ($mxs) ) {
       if($b_server_found == 0){

         //try connection on port 25
         $fp = @fsockopen($mx_host,25, $errno, $errstr, 2);
         if($fp){
           $ms_resp="";
           // say HELO to mailserver
           $ms_resp.=send_command($fp, "HELO microsoft.com");

           // initialize sending mail 
           $ms_resp.=send_command($fp, "MAIL FROM:<support@microsoft.com>");

           // try receipent address, will return 250 when ok..
           $rcpt_text=send_command($fp, "RCPT TO:<".$email.">");
           $ms_resp.=$rcpt_text;
           
           if(substr( $rcpt_text, 0, 3) == "250")
             $b_server_found=1;

           // quit mail server connection
           $ms_resp.=send_command($fp, "QUIT");

         fclose($fp);

         }

       }
    }
  }
  return $b_server_found;
}

function send_command($fp, $out){

  fwrite($fp, $out . "\r\n");
  return get_data($fp);
}

function get_data($fp){
  $s="";
  stream_set_timeout($fp, 2);

  for($i=0;$i<2;$i++)
    $s.=fgets($fp, 1024);

  return $s;
}

// support windows platforms
if (!function_exists ('getmxrr') ) {
  function getmxrr($hostname, &$mxhosts, &$mxweight) {
    if (!is_array ($mxhosts) ) {
      $mxhosts = array ();
    }

    if (!empty ($hostname) ) {
      $output = "";
      @exec ("nslookup.exe -type=MX $hostname.", $output);
      $imx=-1;

      foreach ($output as $line) {
        $imx++;
        $parts = "";
        if (preg_match ("/^$hostname\tMX preference = ([0-9]+), mail exchanger = (.*)$/", $line, $parts) ) {
          $mxweight[$imx] = $parts[1];
          $mxhosts[$imx] = $parts[2];
        }
      }
      return ($imx!=-1);
    }
    return false;
  }
}

?>

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-1

jeff at pzenix dot com ¶

18 years ago

I should point out that the below example won't work with some domains (.co.uk, .org.uk, .net.uk for example) because it assumes (possibly incorrectly) that the format is [ DOMAIN ].[ EXT ].

down

-2

TZ at inpetho dot net ¶

16 years ago

If greylisting is installed on the mx host then he send a "451 4.7.1 Please try again later"

My code fragment:

<?php
//...
foreach ($mx_records as $mx_host) {
    $code = CheckMX($mx_host, $eMail);
    if ($code == 0)    continue; // host not found
    if ($code == 451)    $code = CheckMX($mx_host, $eMail); // Greylisting
    if ($code == 250)    {
        $ok = true;
        break;
    }
}
//...

function CheckMX($mx_host, $eMail)
{
    $code = 0;
    $fp = @fsockopen($mx_host, 25, $errno, $errstr, 2);
    if ($fp)    {
        send_command($fp, 'HELO microsoft.com');
        send_command($fp, 'MAIL FROM:<support@microsoft.com>');
        $erg = send_command($fp, 'RCPT TO:<'.$eMail.'>');
        fclose($fp);
        $code = intval(substr($erg, 0, 3));
    }
    return $code;
}
//...
?>

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-2

rolf at rowi dot net ¶

19 years ago

Be aware that not just user@example.com ist a valid address, also user@subnet.example.com is valid (but maybe less common). Just got into trouble with this check...

Rolf

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