How to send batch bulk emails using Mailgun in PHP.

It is not using Mailgun API, only PHP curl

All receipts are hidden, so they don't see each other emails

No namespace, no composer, just 1 file ready to use.

How to use:

1. add this file "send_mailgun_batch.php"; your PHP project
2. require_once "send_mailgun_batch.php";
3. change $domain and $mailgun_api_key
4. Call this function send_mailgun_batch($emails_to_send_array, $subject, $message);
5. If success you should see a message "Queued. Thank you."