<?php

$db_host = "localhost";
$db_username = "root";
$db_pass = "";
$link= mysqli_connect("$db_host","$db_username","$db_pass", "mydb") or die ("could not connect to mysql");

use PHPMailerPHPMailerPHPMailer;
use PHPMailerPHPMailerException;
// Simply:

//Load Composer's autoloader
require 'vendor/autoload.php';

if(isset($_POST['send'])){

$mail = new PHPMailer(true);                              // Passing `true` enables exceptions
try {
     $query = "select customer_id, customer_name, customer_email from subscribers where flag_email = 0";
     $result = mysqli_query($link, $query) or die("No customer in the table");;

     while($values = mysqli_fetch_array($result)){
         $id = $values['customer_id'];
         $name = $values['customer_name'];
         $toemail = $values['customer_email'];


    //Server settings
    $mail->SMTPDebug = 1;                                 // Enable verbose debug output
    $mail->isSMTP();                                      // Set mailer to use SMTP
    $mail->Host = 'smtp server';  // Specify main and backup SMTP servers
    $mail->SMTPAuth = true;                               // Enable SMTP authentication
    $mail->Username = 'username';                 // SMTP username
    $mail->Password = 'password';                           // SMTP password
    $mail->SMTPSecure = 'tls';                            // Enable TLS encryption, `ssl` also accepted
    $mail->Port = 587;                                    // TCP port to connect to

    //Recipients
    $mail->setFrom('username', 'username');


    $mail->addReplyTo('myemail', 'name');

    $mail->addBCC(''.$toemail.'', ''.$name.'');

    //Content
    $mail->isHTML(true);                                  // Set email format to HTML
    $mail->Subject = 'Here is the subject';
    $mail->Body    = 'Here is the message';


    $mail->send();
    echo 'Message has been sent';
    $upd_query = "update subscribers set flag_email = 1 where customer_id = ".$id."";
    $result= mysqli_query($link, $upd_query);
}

} catch (Exception $e) {
    echo 'Message could not be sent. Mailer Error: ', $mail->ErrorInfo;
}


}