如何调试laravel mailgun

I'm trying to set up mailgun with laravel (5.4) and it's sounds so easy with the docs, but getting it to actually work has been a nightmare and I'm not even sure how to debug the issue.

Here's my situation:

I have guzzle installed.

I can successfully send an email via cURL from my server.

In my config/services.php file I have:

'mailgun' => [
    'domain' => env('MAILGUN_DOMAIN'),
    'secret' => env('MAILGUN_SECRET'),
]

which I have set in my .env file with:

MAILGUN_DOMAIN=https://api.mailgun.net/v3/sandbox...a.mailgun.org
MAILGUN_SECRET=key-926d...746

The driver defaults to mailgun in config/mail.php (I even have it set in my .env file anyways):

'driver' => env('MAIL_DRIVER', 'mailgun')

I have verified my email as an Authorized Recipients in MailGun.

When I log the env values on my server, they are what I am seeing in my .env file.

I've cleared my config cache via php artisan config:clear every time I try a change.

When I go to send mail in a try/catch I get no errors. When I check Mail::failures(); I get nothing.

try {
     $mailSent = Mail::raw('test', function($message) {
         $message->to('<my authorized-email>', 'name');
         $message->subject('testing');
     });
} catch (\Exception $e) {
    dd($e->getMessage());
}

$fail = Mail::failures();

if(!empty($fail)) throw new \Exception('Could not send message to '.$fail[0]);

When I set APP_DEBUG=true and APP_LOG_LEVEL=debug I still get nothing in my log.

From my understanding, I only need to set the driver, domain and secret to use mailguns API (not via smtp) so what I have above is all that I have set.

What can I do to figure out what's failing??