php无法通过php邮件功能接收邮件

我是php新手，我想通过php邮件功能向用户发送邮件，我已经编写了代码，但它不工作，邮件没有收到。我正在本地主机xamp服务器上测试它，下面是我的代码

        <?php include "connection.php";

 if(isset($_POST) & !empty($_POST)){
//print_r($_POST); die;
   $username = mysqli_real_escape_string($conn, $_POST['username']);
   $sql = "SELECT * FROM `users` WHERE username = '$username'";
   $res = mysqli_query($conn, $sql);
   $count = mysqli_num_rows($res);
   if($count == 1){
    echo "Send email to user with password";
   }else{
        echo "User name does not exist in database";
    }

   $r = mysqli_fetch_assoc($res);
     $password = $r['password'];
   $to = $r['username'];
    $subject = "Your Recovered Password";

   $message = "Please use this password to login " . $password;
       $headers = "From :abc23@gmail.com";
      if(mail($to, $subject, $message, $headers)){
        echo "Your Password has been sent to your email id";
       }else{
       echo "Failed to Recover your password, try again";

         } 

        }


     ?> 

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