1. Go to this page and download the library: Download cosmira/envelope library. Choose the download type require.
2. Extract the ZIP file and open the index.php.
3. Add this code to the index.php.
<?php
require_once('vendor/autoload.php');
/* Start to develop here. Best regards https://php-download.com/ */
cosmira / envelope example snippets
use Cosmira\Envelope\Envelope;
$content = file_get_contents('path_to_email_file.eml');
$mail = new Envelope($content);