Почтовая функция не работает

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Мне нужно обновить свою таблицу и отправить почту в обновленную строку.
Таблица успешно обновляется, но не может отправлять почту.

Что я уже пробовал:

<?php 
session_start();

if(isset($_GET['PID'])) {
  $id=$_GET['PID'];

  /* create sql connection*/
  $link = mysqli_connect("localhost", "root", "mysql", "mydb");

  $query = "UPDATE assign t2,
  (   SELECT PID,pname,pemail,ph_no,experience 
      FROM addpandit 
  ) t1
  SET t2.PID = t1.PID,t2.pname = t1.pname,t2.pemail = t1.pemail,t2.ph_no = 
  t1.ph_no,t2.experience = t1.experience
  WHERE t2.PID='' AND t1.PID=$id;"; /*  first query : Notice the 2 semicolons at the end ! */
  $query .= "SELECT *FROM assign WHERE PID=$id"; /* last query : Notice the dot before = at the end ! */

  if (mysqli_multi_query($link, $query)) {
    do {
      /* store first result set */
      if ($result = mysqli_store_result($link)) {
        while ($row = mysqli_fetch_array($result)) {
          $from= 'myemailid@gmail.com';
          $subject= "Accepted ";
  
          $first_name= $row['firstname'];
          $address= $row['address1'];
          $email= $row['email'];
          $phone= $row['phone'];
          $puja= $row['productinfo'];
          $date1= $row['date'];
          $time1= $row['time'];
          $amount= $row['amount'];
          $pname=$row['pname'];
          $pemail=$row['pemail'];
          $ph_no=$row['ph_no'];
          $exp=$row['experience'];	
	
          $msg= "Dear $first_name Your order has been accepted.\nPlease check the details and do payment\n 
            Name:$first_name\n
            Email:$email\n
            Mobile No:$phone\n
            Selected Puja:$puja\n
            Date:$date1\n
            Time:$time1\n
            Amount:$amount\nThank You";

          $sendmail=mail($email, $subject, $msg, 'From:' . $from);

          if($sendmail) {
            echo 'Email sent to: ' . $email. '<br>';
          }
          else {
            echo 'email not sent';
          }
        }
        mysqli_free_result($result);
      }   
    } while (mysqli_next_result($link));
  }
}
?>

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