add PostMark driver to laravel Mail facades
composer require cammac/postmark
if your Laravel below 5.5 you need to add PostMarkServiceProvider
in config/app.php in providers list
\Cammac\Postmark\PostMarkServiceProvider::class,
In .env file change MAIL_DRIVER to "postmark"
MAIL_DRIVER=postmark
POSTMARK_SECRET=your-api-token
This package is open-sourced software licensed under the MIT license.