Exemplo de uso Class PHP criada para envio simples de email via API Mailgun

Sender-mailgun.php

<?php
require_once('SenderMailgun.php');

# Open file key
$key = file_get_contents('key');

# Instantiate the client.
SenderMailgun::$api_key = $key;

# Data params email.
$params = [
  'from'=> 'Your Name <you@maketing.your.ecommerce.br>',
  'to'=>'your-client@gmail.com',
  'subject'=>'Your subject',
  'html'=>'<h1>Black Friday!!!</h1>'
];

# Action sender.
SenderMailgun::send_mail('marketing.imaginarionerd.com.br',$params);
print_r(SenderMailgun::$result_send);
exit();

Class SenderMailgun in PHP

https://blog.mrcl0wn.com/2020/04/class-sendermailgun-in-php.html