用php发送信息

I have a simple password send that will send them their password when they enter their email but the only problem is that I am getting an error when I load the page that says

Failed to add recipient: @localhost [SMTP: Invalid response code received from server (code: 501, response: <@localhost>: no local part)]

I know that the information is correct. Here is the code- (Yes I know not using mysqli is insecure. This is for a quick thing.)

 <?php
  $username = "sdfsdfsdf";
  $password = "sdfsdfsdf";
  $hostname = "dsfsdfsdf";    
  $dbconn = mysql_connect($hostname, $username, $password) or die("Unable to connect to MySQL");
  $emailto  = $_POST['email'];

  $database = mysql_select_db("jjlliinn_test",$dbconn);

  $query  = "SELECT password FROM agentclient WHERE email = '$emailto'";
  $result = mysql_query($query) or die(mysql_error());
  $data = mysql_fetch_assoc($result);



// // // // // // // // // // // // // // // // // // // // // // // // // // // // // // // // // // // // // // // // // // 
 require_once "Mail.php";

 $from = "JLP <no-reply@sdfsdfsdfsdfsdfsdfsdf.net>";
 $to = "$toemail";
 $subject = "Your password";
 $body = "Hi,

Your password is $data.";

 $mailhost = "mail.sdfsdfsdfsdf.net";
 $mailusername = "no-reply@sdfsdfsdfsdf.net";
 $mailpassword = "Uq?sdfsdfsdfsdfsdf-";

 $headers = array ('From' => $from,
   'To' => $to,
   'Subject' => $subject);
 $smtp = Mail::factory('smtp',
   array ('host' => $mailhost,
     'auth' => true,
     'username' => $mailusername,
     'password' => $mailpassword));

 $mail = $smtp->send($to, $headers, $body);

 if (PEAR::isError($mail)) {
   echo("<p>" . $mail->getMessage() . "</p>");
  } else {
   echo("<p>Password successfully sent!</p>");
  }
    mysql_close($dbconn);  
 ?>

Your code sends any email to localhost, due to this typo:

 $to = "$toemail"; # empty-string assignment! Should be "$emailto"