使用sock技术发邮件，无需服务器支持。速度快！！ 

function send_mail($to,$subject,$body)   
{   
/////////////Smtp信息，可以修改成你的，//////////   
   $loc_host = "longbill";        //发信计算机名，可随意   
  $smtp_acc = "longbill.mail";   //Smtp认证的用户名，   
  $smtp_pass = "longbill";         //Smtp认证的密码，   
  $smtp_host = "smtp.163.com";     //SMTP服务器地址，   
  $from = "longbill.mail@163.com"; //要与smtp信息对应 ,否则会失败   
/////////////Smtp信息完//////////////////////////////////    
  $headers = "Content-Type: text/plain; charset=\"gb2312\"\r\nContent-Transfer-Encoding: base64";   
  $lb="\r\n";                    //linebreak   
  $hdr = explode($lb,$headers);  //解析后的hdr   
  if($body)   
  {   
    $bdy = preg_replace("/^\./","..",explode($lb,$body));   
  }//解析后的Body   
  $smtp = array(   
  //1、EHLO，期待返回220或者250   
  array("EHLO ".$loc_host.$lb,"220,250","HELO error: "),   
  //2、发送Auth Login，期待返回334   
  array("AUTH LOGIN".$lb,"334","AUTH error:"),   
  //3、发送经过Base64编码的用户名，期待返回334   
  array(base64_encode($smtp_acc).$lb,"334","AUTHENTIFICATION error : "),   
  //4、发送经过Base64编码的密码，期待返回235   
  array(base64_encode($smtp_pass).$lb,"235","AUTHENTIFICATION error : "));   
 //5、发送Mail From，期待返回250   
 $smtp[] = array("MAIL FROM: <".$from.">".$lb,"250","MAIL FROM error: ");   
 //6、发送Rcpt To。期待返回250   
 $smtp[] = array("RCPT TO: <".$to.">".$lb,"250","RCPT TO error: ");   
 //7、发送DATA，期待返回354   
 $smtp[] = array("DATA".$lb,"354","DATA error: ");   
 //8.0、发送From   
 $smtp[] = array("From: ".$from.$lb,"","");   
 //8.2、发送To   
 $smtp[] = array("To: ".$to.$lb,"","");   
 //8.1、发送标题   
 $smtp[] = array("Subject: ".$subject.$lb,"","");   
 //8.3、发送其他Header内容   
 foreach($hdr as $h) {$smtp[] = array($h.$lb,"","");}   
 //8.4、发送一个空行，结束Header发送   
 $smtp[] = array($lb,"","");   
 //8.5、发送信件主体   
 if($bdy)   
 {   
   foreach($bdy as $b)    
   {   
     $smtp[] = array(base64_encode($b.$lb).$lb,"","");   
   }   
 }   
 //9、发送“.”表示信件结束，期待返回250   
 $smtp[] = array(".".$lb,"250","DATA(end)error: ");   
 //10、发送Quit，退出，期待返回221   
 $smtp[] = array("QUIT".$lb,"221","QUIT error: ");   
 //打开smtp服务器端口   
 $fp = @fsockopen($smtp_host, 25);   
 if (!$fp) echo "<b>Error:</b> Cannot conect to ".$smtp_host."<br>";   
 while($result = @fgets($fp, 1024))   
 {   
    if(substr($result,3,1) == " ") { break; }   
 }   
 $result_str="";   
 //发送smtp数组中的命令/数据   
 foreach($smtp as $req)   
 {   
  //发送信息   
  @fputs($fp, $req[0]);   
  //如果需要接收服务器返回信息，则   
  if($req[1])   
  {   
   //接收信息   
   while($result = @fgets($fp, 1024))   
    {   
      if(substr($result,3,1) == " ") { break; }   
    }   
    if (!strstr($req[1],substr($result,0,3)))   
    {   
      $result_str.=$req[2].$result."<br>";   
    }   
   }   
 }   
 //关闭连接   
 @fclose($fp);   
 if ($result_str==""){return "发送成功!!";}else {return $result_str;}   
}