getmxrr for email address validation

[sKunKbad]

I've been checking out getmxrr() and the associated comments on php.net, and wondering if the following code, which was given to me, is going to work well or get me in trouble:

 

<?php
// validate the f0rm before submitting

// hardcore e-mail validation
  function MailVal($Addr, $Level, $Timeout = 15000) { 

//  Valid Top-Level Domains 
    $gTLDs = "com:net:org:edu:gov:mil:int:arpa:"; 
    $CCs   = "ad:ae:af:ag:ai:al:am:an:ao:aq:ar:as:at:au:aw:az:ba:bb:bd:be:bf:". 
             "bg:bh:bi:bj:bm:bn:bo:br:bs:bt:bv:bw:by:bz:ca:cc:cf:cd:cg:ch:ci:". 
             "ck:cl:cm:cn:co:cr:cs:cu:cv:cx:cy:cz:de:dj:dk:dm:do:dz:ec:ee:eg:". 
             "eh:er:es:et:fi:fj:fk:fm:fo:fr:fx:ga:gb:gd:ge:gf:gh:gi:gl:gm:gn:". 
             "gp:gq:gr:gs:gt:gu:gw:gy:hk:hm:hn:hr:ht:hu:id:ie:il:in:io:iq:ir:". 
             "is:it:jm:jo:jp:ke:kg:kh:ki:km:kn:kp:kr:kw:ky:kz:la:lb:lc:li:lk:". 
             "lr:ls:lt:lu:lv:ly:ma:mc:md:mg:mh:mk:ml:mm:mn:mo:mp:mq:mr:ms:mt:". 
             "mu:mv:mw:mx:my:mz:na:nc:ne:nf:ng:ni:nl:no:np:nr:nt:nu:nz:om:pa:". 
             "pe:pf:pg:ph:pk:pl:pm:pn:pr:pt:pw:py:qa:re:ro:ru:rw:sa:sb:sc:sd:". 
             "se:sg:sh:si:sj:sk:sl:sm:sn:so:sr:st:su:sv:sy:sz:tc:td:tf:tg:th:". 
             "tj:tk:tm:tn:to:tp:tr:tt:tv:tw:tz:ua:ug:uk:um:us:uy:uz:va:vc:ve:". 
             "vg:vi:vn:vu:wf:ws:ye:yt:yu:za:zm:zr:zw:"; 

//  The countries can have their own 'TLDs', e.g. mydomain.com.au 
    $cTLDs = "com:net:org:edu:gov:mil:co:ne:or:ed:go:mi:"; 

    $fail = 0; 

//  Shift the address to lowercase to simplify checking 
    $Addr = strtolower($Addr); 

//  Split the Address into user and domain parts 
    $UD = explode("@", $Addr); 
    if (sizeof($UD) != 2 || !$UD[0]) $fail = 1; 

//  Split the domain part into its Levels 
    $Levels = explode(".", $UD[1]); $sLevels = sizeof($Levels); 
    if ($sLevels < 2) $fail = 1; 

//  Get the TLD, strip off trailing ] } ) > and check the length 
    $tld = $Levels[$sLevels-1]; 
    $tld = ereg_replace("[>)}]$|]$", "", $tld); 
    if (strlen($tld) < 2 || strlen($tld) > 3 && $tld != "arpa") $fail = 1; 

    $Level--; 

//  If the string after the last dot isn't in the generic TLDs or country codes, it's invalid. 
    if ($Level && !$fail) { 
    $Level--; 
    if (!ereg($tld.":", $gTLDs) && !ereg($tld.":", $CCs)) $fail = 2; 
    } 

//  If it's a country code, check for a country TLD; add on the domain name. 
    if ($Level && !$fail) { 
    $cd = $sLevels - 2; $domain = $Levels[$cd].".".$tld; 
    if (ereg($Levels[$cd].":", $cTLDs)) { $cd--; $domain = $Levels[$cd].".".$domain; } 
    } 

//  See if there's an MX record for the domain 
    if ($Level && !$fail) { 
    $Level--; 
    if (!getmxrr($domain, $mxhosts, $weight)) $fail = 3; 
    } 

//  Attempt to connect to port 25 on an MX host 
    if ($Level && !$fail) { 
    $Level--; 
    while (!$sh && list($nul, $mxhost) = each($mxhosts)) 
      $sh = fsockopen($mxhost, 25); 
    if (!$sh) $fail = 4; 
    } 

//  See if anyone answers 
    if ($Level && !$fail) { 
    $Level--; 
    set_socket_blocking($sh, false); 
    $out = ""; $t = 0; 
    while ($t++ < $Timeout && !$out) 
      $out = fgets($sh, 256); 
    if (!ereg("^220", $out)) $fail = 5; 
    } 

    if ($sh) fclose($sh); 

    return $fail; 
  } // End E-Mail Validation Function

?>

 

I've tested it using a few email addresses, and so far it works as expected, but the php.net page for getmxrr says not to use getmxrr for email validation. I'm getting a rediculous amount of spam, and I need some sort of better email address validation. Currently, my $Level is set to 4.