本文提供的这个php email验证类，具有如下的特点： 1，可以作简单的email地址验证。 2，可以验证email地址是否属于一个有效的邮件交换记录域。 3，可以通过尝试连接邮件服务器，来检测邮箱是否真实存在。 4，对于windows平台，实现了getmxrr不具备的功能，用到了Moriyoshi Koizumi的 DNS 解析类。

代码：

next_token; 
        } 
        for($character=0;$characternext_token=substr($string,$found+1); 
            return(substr($string,0,$found)); 
        } 
        else 
        { 
            $this->next_token=""; 
            return($string); 
        } 
    } 

    Function OutputDebug($message) 
    { 
        $message.="\n"; 
        if($this->html_debug) 
            $message=str_replace("\n","
\n",HtmlEntities($message)); 
        echo $message; 
        flush(); 
    } 

    Function GetLine($connection) 
    { 
        for($line="";;) 
        { 
            if(feof($connection)) 
                return(0); 
            $line.=fgets($connection,100); 
            $length=strlen($line); 
            if($length>=2 
            && substr($line,$length-2,2)=="\r\n") 
            { 
                $line=substr($line,0,$length-2); 
                if($this->debug) 
                    $this->OutputDebug("S $line"); 
                return($line); 
            } 
        } 
    } 

    Function PutLine($connection,$line) 
    { 
        if($this->debug) 
            $this->OutputDebug("C $line"); 
        return(fputs($connection,"$line\r\n")); 
    } 

    Function ValidateEmailAddress($email) 
    { 
        if(IsSet($this->preg)) 
        { 
            if(strlen($this->preg)) 
                return(preg_match($this->preg,$email)); 
        } 
        else 
        { 
            $this->preg=(function_exists("preg_match") ? "/".str_replace("/", "\\/", $this->email_regular_expression)."/" : ""); 
            return($this->ValidateEmailAddress($email)); 
        } 
        return(eregi($this->email_regular_expression,$email)!=0); 
    } 

    Function ValidateEmailHost($email,&$hosts) 
    { 
        if(!$this->ValidateEmailAddress($email)) 
            return(0); 
        $user=$this->Tokenize($email,"@"); 
        $domain=$this->Tokenize(""); 
        $hosts=$weights=array(); 
        $getmxrr=$this->getmxrr; 
        if(function_exists($getmxrr) 
        && $getmxrr($domain,$hosts,$weights)) 
        { 
            $mxhosts=array(); 
            for($host=0;$hostexclude_address)==0 
            || strcmp(@gethostbyname($this->exclude_address),$ip))) 
                $hosts[]=$domain; 
        } 
        return(count($hosts)!=0); 
    } 

    Function VerifyResultLines($connection,$code) 
    { 
        while(($line=$this->GetLine($connection))) 
        { 
            $this->last_code=$this->Tokenize($line," -"); 
            if(strcmp($this->last_code,$code)) 
                return(0); 
            if(!strcmp(substr($line, strlen($this->last_code), 1)," ")) 
                return(1); 
        } 
        return(-1); 
    } 

    Function ValidateEmailBox($email) 
    { 
        if(!$this->ValidateEmailHost($email,$hosts)) 
            return(0); 
        if(!strcmp($localhost=$this->localhost,"") 
        && !strcmp($localhost=getenv("SERVER_NAME"),"") 
        && !strcmp($localhost=getenv("HOST"),"")) 
           $localhost="localhost"; 
        if(!strcmp($localuser=$this->localuser,"") 
        && !strcmp($localuser=getenv("USERNAME"),"") 
        && !strcmp($localuser=getenv("USER"),"")) 
           $localuser="root"; 
        for($host=0;$hostdebug) 
                    $this->OutputDebug("Resolving host name \"".$hosts[$host]."\"..."); 
                if(!strcmp($ip=@gethostbyname($domain),$domain)) 
                { 
                    if($this->debug) 
                        $this->OutputDebug("Could not resolve host name \"".$hosts[$host]."\"."); 
                    continue; 
                } 
            } 
            if(strlen($this->exclude_address) 
            && !strcmp(@gethostbyname($this->exclude_address),$ip)) 
            { 
                if($this->debug) 
                    $this->OutputDebug("Host address of \"".$hosts[$host]."\" is the exclude address"); 
                continue; 
            } 
            if($this->debug) 
                $this->OutputDebug("Connecting to host address \"".$ip."\"..."); 
            if(($connection=($this->timeout ? @fsockopen($ip,25,$errno,$error,$this->timeout) : @fsockopen($ip,25)))) 
            { 
                $timeout=($this->data_timeout ? $this->data_timeout : $this->timeout); 
                if($timeout 
                && function_exists("socket_set_timeout")) 
                    socket_set_timeout($connection,$timeout,0); 
                if($this->debug) 
                    $this->OutputDebug("Connected."); 
                if($this->VerifyResultLines($connection,"220")>0 
                && $this->PutLine($connection,"HELO $localhost") 
                && $this->VerifyResultLines($connection,"250")>0 
                && $this->PutLine($connection,"MAIL FROM: <$localuser@$localhost>") 
                && $this->VerifyResultLines($connection,"250")>0 
                && $this->PutLine($connection,"RCPT TO: <$email>") 
                && ($result=$this->VerifyResultLines($connection,"250"))>=0) 
                { 
                    if($result) 
                    { 
                        if($this->PutLine($connection,"DATA")) 
                            $result=($this->VerifyResultLines($connection,"354")!=0); 
                    } 
                    else 
                    { 
                        if(strlen($this->last_code) 
                        && !strcmp($this->last_code[0],"4")) 
                            $result=-1; 
                    } 
                    if($this->debug) 
                        $this->OutputDebug("This host states that the address is ".($result ? ($result>0 ? "valid" : "undetermined")
 : "not valid")."."); 
                    fclose($connection); 
                    if($this->debug) 
                        $this->OutputDebug("Disconnected."); 
                    return($result); 
                } 
                if($this->debug) 
                    $this->OutputDebug("Unable to validate the address with this host."); 
                fclose($connection); 
                if($this->debug) 
                    $this->OutputDebug("Disconnected."); 
            } 
            else 
            { 
                if($this->debug) 
                    $this->OutputDebug("Failed."); 
            } 
        } 
        return(-1); 
    } 
}; 

?> 

//GetMXRR function emulation need to make the class work properly under Windows and other platforms without this function
 (needs DNS.php mentioned in the Related links section).


 
   All Rights Reserved. 

   This library is free software; you can redistribute it and/or modify it 
   under the terms of the GNU Lesser General Public License as published 
   by the Free Software Foundation; either version 2.1 of the License, or any 
   later version. 

   This library is distributed in the hope that it will be useful, but 
   WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 
   or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public 

   License for more details. 

   You should have received a copy of the GNU Lesser General Public License 
   along with this library; if not, 
   write to the Free Software Foundation, Inc., 
   59 Temple Place, Suite 330, Boston, MA 02111-1307  USA 

  ------------------------------------------------------------------------ */ 

    if(IsSet($_NAMESERVERS) 
    && (GetType($_NAMESERVERS)!="array" 
    || count($_NAMESERVERS)==0)) 
        Unset($_NAMESERVERS); 

/*************************************************************************** 
 Description 

  $_NAMESERVER[] 

    The array that contains IP addresses or domain names of name servers 
    used for DNS resolution. 
    If nothing is set before require()'ing this library, the values will 
    automatically prepared. 

  bool getmxrr( string $hostname, arrayref $mxhosts, arrayref $weight ); 

    This function works in the same way as getmxrr(), however the 
    third parameter cannot be omitted. If you need no MX preference 
    information, please do like: 


           getmxrr( 'example.com', $mxhosts, ${''} ); 

 ------------------------------------------------------------------------- 
 Configuration 

  If you are doing with win32 environments and don't set $_NAMESERVER 
  manually, make sure that ipconfig.exe is within the PATH. 
  ipconfig.exe is generally distributed with any Microsoft(R) Windows 
  distributions except for Windows 95. 

 ***************************************************************************/ 

    require_once( 'DNS.php' ); 

    /* rewrite this path to the same as the box's configuration 
       if you run scripts on *NIX platforms */ 
    define( 'RESOLV_CONF_PATH', '/etc/resolv.conf' ); 

    if( !isset( $_NAMESERVERS ) ) { 
        $_NAMESERVERS = array(); 
        if( strncmp( PHP_OS, "WIN", 3 ) == 0 ) { 
            unset( $res ); 
            exec( 'ipconfig /all', $res ); 
            $cnt = count( $res ); 
            for( $i = 0; $i < $cnt; ++$i ) { 
                if( strpos( $res[$i], 'DNS Servers' ) !== false ) { 
                    $_NAMESERVERS[] = substr( $res[$i], strpos( $res[$i], ': ' ) + 2 ); 
                    break; 
                } 
            } 
            while( $i<$cnt-1 && strpos( $res[++$i], ':' ) === false ) { 
                $_NAMESERVERS[] = trim( $res[$i] ); 
            } 
        } elseif( file_exists( RESOLV_CONF_PATH ) ) { 
            $lines = file( RESOLV_CONF_PATH ); 
            $cnt = count( $lines ); 
            for( $i = 0; $i < $cnt; ++$i ) { 
                list( $dr, $val ) = split( '[ \t]', $lines[$i] ); 
                if( $dr == 'nameserver' ) { 
                    $_NAMESERVERS[] = rtrim( $val ); 
                } 
            } 
            unset( $lines ); 
        } 
    } 

    if(count($_NAMESERVERS)) 
        $__PHPRESOLVER_RS = new DNSResolver( $_NAMESERVERS[0] ); 
    else 
    { 
        Unset($_NAMESERVERS); 
        Unset($__PHPRESOLVER_RS); 
    } 

    function GetMXRR( $hostname, &$mxhosts, &$weight ) { 
        global $__PHPRESOLVER_RS; 
        if(!IsSet($__PHPRESOLVER_RS)) 
            return(false); 
        $dnsname = & DNSName::newFromString( $hostname ); 
        $answer = & $__PHPRESOLVER_RS->sendQuery( 
          new DNSQuery( 
            new DNSRecord( $dnsname, DNS_RECORDTYPE_MX ) 
          ) 
        ); 
        if( $answer === false || $answer->rec_answer === false ) { 
            return false; 
        } else { 
            $i = count( $answer->rec_answer ); 
            $mxhosts = $weight = array(); 
            while( --$i >= 0 ) { 
                if( $answer->rec_answer[$i]->type == DNS_RECORDTYPE_MX ) { 
                    $rec = &$answer->rec_answer[$i]->specific_fields; 
                    $mxhosts[] = substr( $rec['exchange']->getCanonicalName(), 0, -1 ); 
                    $weight[] = $rec['preference']; 
                } 
            } 
            return true; 
        } 
    } 

?> 



//TEST SCRIPT 


 
 
 
 
 
Test for Manuel Lemos's PHP E-mail validation class
 
 
getmxrr="_getmxrr"; 
    } 
    */ 

    /* how many seconds to wait before each attempt to connect to the 
       destination e-mail server */ 
    $validator->timeout=10; 

    /* how many seconds to wait for data exchanged with the server. 
       set to a non zero value if the data timeout will be different 
         than the connection timeout. */ 
    $validator->data_timeout=0; 

    /* user part of the e-mail address of the sending user 
       (info@phpclasses.org in this example) */ 
    $validator->localuser="info"; 

    /* domain part of the e-mail address of the sending user */ 
    $validator->localhost="phpclasses.org"; 

    /* Set to 1 if you want to output of the dialog with the 
       destination mail server */ 
    $validator->debug=1; 

    /* Set to 1 if you want the debug output to be formatted to be 
    displayed properly in a HTML page. */ 
    $validator->html_debug=1; 


    /* When it is not possible to resolve the e-mail address of 
       destination server (MX record) eventually because the domain is 
       invalid, this class tries to resolve the domain address (A 
       record). If it fails, usually the resolver library assumes that 
       could be because the specified domain is just the subdomain 
       part. So, it appends the local default domain and tries to 
       resolve the resulting domain. It may happen that the local DNS 
       has an * for the A record, so any sub-domain is resolved to some 
       local IP address. This  prevents the class from figuring if the 
       specified e-mail address domain is valid. To avoid this problem, 
       just specify in this variable the local address that the 
       resolver library would return with gethostbyname() function for 
       invalid global domains that would be confused with valid local 
       domains. Here it can be either the domain name or its IP address. */ 
    $validator->exclude_address=""; 

    if(IsSet($_GET["email"])) 
        $email=$_GET["email"]; 
    if(IsSet($email) 
    && strcmp($email,"")) 
    { 
        if(($result=$validator->ValidateEmailBox($email))<0) 
            echo "
It was not possible to determine if $email is a valid deliverable e-mail box address.
\n"; 
        else 
            echo "
$email is ".($result ? "" : "not ")."a valid deliverable e-mail box address.
\n"; 
    } 
    else 
    { 
        $port=(strcmp($port=getenv("SERVER_PORT"),"") ? intval($port) : 80); 
        $site="http://".(strcmp($site=getenv("SERVER_NAME"),"") ? $site : "localhost").($port==80 ? "" : ":".$port).GetEnv("REQUEST_URI"); 
        echo "
Access this page using a URL like: $site?email=your@test.email.here
\n"; 
    } 
?>