How to add custom Mail Driver to Laravel

Tested on Laravel 5.8

Within the source code of laravel 5.8 at this time of writing, we have this following

<?php

namespace Illuminate\Support;
// use...

abstract class Manager
{
  //somewhere in the body ...
  
      /**
     * Register a custom driver creator Closure.
     *
     * @param  string    $driver
     * @param  \Closure  $callback
     * @return $this
     */
    public function extend($driver, Closure $callback)
    {
        $this->customCreators[$driver] = $callback;

        return $this;
    }
    
    // the rest of the code...
}

it means we can easily extend the driver using this manager class!

Create a MailDriver class

In this case I am using OutlookMailDriver, and since i am going to use the extend method from the existing manager, it expects a Closure therefore i make an invocable method that return a function.

<?php
declare(strict_types=1);

namespace App\Helpers\Drivers;


use App\Helpers\Transports\OutlookTransportManager;
use Illuminate\Mail\TransportManager;

class OutlookMailDriver
{
    public function __invoke(TransportManager $manager)
    {
        return function ($app) {
            $config = $app['config']->get('services.outlook', []);
            return new OutlookTransportManager($config);
        };
    }
}

The signature of your invocable may differ from mine

Create a CustomMailProvider that extend Illuminate\Mail\MailServiceProvider

I am going to override the registerSwiftTransport method yet calling its parent first to have it registered its expected Manager then I extend it with my custom Mail Driver.

<?php

namespace App\Providers;

use App\Helpers\Drivers\OutlookMailDriver;
use Illuminate\Mail\MailServiceProvider;
use Illuminate\Mail\TransportManager;

class CustomMailProvider extends MailServiceProvider
{
    /**
     * Register the Swift Transport instance.
     *
     * @return void
     */
    protected function registerSwiftTransport()
    {
        parent::registerSwiftTransport();
        
        $this->app->extend('swift.transport', function (TransportManager $transport) {
            $driver = 'outlook';
            $callback = new OutlookMailDriver();
            $transport->extend($driver, $callback($transport));
            return $transport;
        });
    }
}

Create a class that extends Illuminate\Mail\Transport\Transport

Since Illuminate\Mail\Transport\Transport is an abstract class therefore i need to have send method.

<?php
declare(strict_types=1);

namespace App\Helpers\Transports;

use Illuminate\Mail\Transport\Transport;
use Swift_Mime_SimpleMessage;

class OutlookTransportManager extends Transport
{

    public function __construct($config)
    {
        // do your whatever you need here
    }
    
    public function send(Swift_Mime_SimpleMessage $message, &$failedRecipients = null)
    {
        logger('I am using custom outlook manager');
        // TODO: Implement send() method.
        return 0;
    }
}

Register the CustomMailProvider in your config/app.php

comment Illuminate\Mail\MailServiceProvider::class within your config, and register your own custom provider there

return [
    'providers' => [
        //...
        App\Providers\CustomMailProvider::class,
        //Illuminate\Mail\MailServiceProvider::class, // comment this out
    ],
];

Test

// somewhere in your route/web.php

Route::get('test', function () {
    Mail::to('[email protected]')->send(new \App\Mail\Test());
});