Laravel 5.4 Mailgun integration throws 401 Forbidden error when attempting to send emails

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1

I’m working on a Laravel 5.4 application and trying to integrate Mailgun for email delivery. However, I keep getting a 401 Forbidden error whenever I attempt to send an email.

The error message I’m receiving is:

RequestException.php line 111: Client error: POST https://api.mailgun.net/v3/sandbox123abc456def789ghi012jkl345mno.mailgun.org/messages.mime resulted in a 401 UNAUTHORIZED response: Forbidden

Here’s my current setup:

.env configuration:

MAIL_DRIVER=mailgun
MAILGUN_DOMAIN=sandbox123abc456def789ghi012jkl345mno.mailgun.org
MAILGUN_SECRET=key-987f654e**********

mail.php settings:

'driver' => env('MAIL_DRIVER', 'smtp'),
'host' => env('MAIL_HOST', 'smtp.mailgun.org'),
'port' => env('MAIL_PORT', 587),
'from' => [
    'address' => env('MAIL_FROM_ADDRESS', '[email protected]'),
    'name' => env('MAIL_FROM_NAME', 'John Doe'),
],

services.php configuration:

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

Test route for sending email:

Route::get('/test-email', function () {
    $emailData = [
        'subject' => 'Welcome to our platform',
        'message' => 'Thank you for joining us. We are excited to have you on board!'
    ];

    Mail::send('emails.welcome', $emailData, function($mail){
        $mail->to('[email protected]', 'Test User')->subject('Welcome Message');
    });
});

I have guzzlehttp/guzzle version 6.2 installed as well. When I visit the test route, the 401 error occurs. I’ve double checked my Mailgun credentials and domain settings but can’t seem to resolve this issue. Has anyone encountered this problem before?

2

Had this exact problem last month switching from SendGrid to Mailgun. Super frustrating - turns out Laravel 5.4’s Mailgun driver uses the wrong HTTP auth method. Here’s the fix: you need to manually set the API key format. In services.php, update your Mailgun config like this: ‘mailgun’ => [ ‘domain’ => env(‘MAILGUN_DOMAIN’), ‘secret’ => ‘api:’ . env(‘MAILGUN_SECRET’), ], See that ‘api:’ prefix? Mailgun’s REST API needs that for HTTP basic auth, but Laravel’s driver doesn’t add it automatically in 5.4. Don’t forget to clear your config cache: php artisan config:clear. Fixed my 401 errors instantly without changing anything else.

3

Laravel + Mailgun auth issues are the worst - too many parts that fail without telling you why.

Hit the same 401 hell last year. Wasted hours on Laravel’s mail config and Mailgun’s weird auth requirements.

Fixed it by scrapping Laravel’s mail system completely. Now I use Latenode for all email stuff.

Super simple: Laravel shoots email data to a Latenode workflow via HTTP, Latenode talks to Mailgun’s API directly. No more driver issues or auth formatting headaches.

You get real error handling, auto-retries, and proper logs without touching mail.php or services.php. Debugging’s way easier when you can actually see what’s happening in Latenode’s dashboard.

15 minutes to build the workflow and hook it up. Beats wrestling with config files any day.

4

That 401 error is usually credentials, but debugging Laravel email is a nightmare with all those config files and environment variables.

I’ve dealt with this exact mess before. Instead of fighting Laravel’s mail config and Mailgun’s API weirdness, I just automated everything with Latenode.

Here’s what I did: created a webhook endpoint in Laravel that receives email requests, then let Latenode handle the actual delivery through Mailgun. No more wrestling with Laravel’s mail driver setup or credential headaches.

Super simple workflow: my app sends a POST to Latenode with email data, Latenode processes and sends via Mailgun’s API directly. Takes 10 minutes to set up and you’re done with mail.php and services.php forever.

Bonus: you get retry logic, delivery tracking, and error handling built-in. Way cleaner than debugging Laravel’s mail system.

5

Double-check you’re not mixing up test and live API credentials. I spent hours debugging a similar 401 issue - turned out I was using sandbox domain with production API key from a different project. Some hosting providers cache environment variables aggressively too. Even after updating your .env file, old credentials might still be loaded. Try dumping your actual config values with dd(config(‘services.mailgun’)) to see what Laravel’s actually using versus what you think you’ve set. There’s often a disconnect between .env updates and what loads, especially with config caching enabled or on shared hosting.

6

Check your API endpoint region first - Mailgun has separate US/EU endpoints and using the wrong one throws 401s even with valid credentials. Also verify your from address is authorized in the Mailgun dashboard. Sandbox domains are really strict about sender verification.