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    getmxrr

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

    getmxrr — 指定したインターネットホスト名に対応する MX レコードを取得する

    説明

    getmxrr(string $hostname, array &$hosts, array &$weights = null): bool

    hostname に対応する MX レコードを DNS から探します。

    パラメータ

    hostname

    インターネットホスト名。

    hosts

    見つかった MX レコードのリストが、配列 hosts に格納されます。

    weights

    配列 weights を指定すると、 そこに重み情報が格納されます。

    戻り値

    何かレコードが見つかった場合に true、 何も見つからないかエラーが発生した場合に false を返します。

    注意

    注意:

    この関数をメールアドレスの確認の目的で使用すべきではありません。 DNS が検出したメールエクスチェンジャーを返すだけです。 しかし、» RFC 2821 によれば、 メールエクスチェンジャーがひとつも見つからなければ、 hostname 自体が唯一のメールエクスチェンジャー であるとみなされ、その優先度は 0（最高）となります。

    注意:

    この関数が実装される前の Windows での互換性を保つには、 » PEAR の » Net_DNS クラスを試してみてください。

    参考

    • checkdnsrr() - 指定したインターネットホスト名もしくは IP アドレスに対応する DNS レコードを検索する
    • dns_get_record() - ホスト名に関連する DNS リソースレコードを取得する
    • gethostbyname() - インターネットホスト名に対応するIPv4アドレスを取得する
    • gethostbynamel() - 指定したインターネットホスト名に対応するIPv4アドレスのリストを取得する
    • gethostbyaddr() - 指定した IP アドレスに対応するインターネットホスト名を取得する
    • named(8) のマニュアルページ

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    User Contributed Notes 19 notes

    up
    17
    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 ...
    up
    3
    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.
    up
    11
    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
    )

    )
    up
    3
    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.
    up
    1
    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);

    ?>
    up
    0
    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 );
    }
    up
    1
    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 );
    ?>
    up
    0
    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
    up
    0
    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
    up
    0
    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 ;)
    up
    0
    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';
    up
    0
    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.
    up
    -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");

    }
    ?>
    up
    -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
    up
    -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;
    }
    ?>
    up
    -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;
    }
    }

    ?>
    up
    -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 ].
    up
    -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;
    }
    //...
    ?>
    up
    -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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