Send bulk mail by mailgun api in php

bulkmailbymailgun.php

<?php
define('MAILGUN_URL', 'https://api.mailgun.net/v3/DOMAIN_NAME');
define('MAILGUN_KEY', 'KEY'); 

function sendBulkMailByMailGun($emailArr = array(), $subject, $html, $text = '', $replyto = EMAIL_INFO, $mailcat = 'test', $mailfrom = FROM, $mailfromname = FROMNAME) {
  
    $emails_arr = array();
   	if ($emailArr) {
		$i=1;
		foreach ($emailArr as $email) {
		    $email_arr .= $email.',';
		    $email_data[$email]['id'] = $i;
		    $i++; 
		}
		$email_arr = ltrim($email_arr, ',');
    }
    $email_data = json_encode($email_data);
    $array_data = array(
		'from'=> $mailfromname .'<'.$mailfrom.'>',
		'to'=>$email_arr,
		'subject'=>$subject,
		'html'=>$html,
		'text'=>$text,
		'o:tracking'=>'yes',
		'o:tracking-clicks'=>'yes',
		'o:tracking-opens'=>'yes',
		'o:tag[1]'=>$mailcat,
		'o:tag[2]'=>'tag2',
		'h:Reply-To'=>$replyto,
		'recipient-variables'=>$email_data
    );
    $session = curl_init(MAILGUN_URL.'/messages');
    curl_setopt($session, CURLOPT_HTTPAUTH, CURLAUTH_BASIC);
  	curl_setopt($session, CURLOPT_USERPWD, 'api:'.MAILGUN_KEY);
    curl_setopt($session, CURLOPT_POST, true);
    curl_setopt($session, CURLOPT_POSTFIELDS, $array_data);
    curl_setopt($session, CURLOPT_HEADER, false);
    curl_setopt($session, CURLOPT_ENCODING, 'UTF-8');
    curl_setopt($session, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($session, CURLOPT_SSL_VERIFYPEER, false);
    $response = curl_exec($session);
    curl_close($session);
    $results = json_decode($response, true);
    return $results;
}







?>