Use a custom service provider for email configuration

src/Foundation/InstalledSite.php

@@ -40,7 +40,6 @@
 use Illuminate\Filesystem\Filesystem;
 use Illuminate\Filesystem\FilesystemServiceProvider;
 use Illuminate\Hashing\HashServiceProvider;
-use Illuminate\Mail\MailServiceProvider;
 use Illuminate\Validation\ValidationServiceProvider;
 use Illuminate\View\ViewServiceProvider;
 use Monolog\Formatter\LineFormatter;
@@ -118,18 +117,6 @@ private function bootLaravel(): Application
         $laravel->register(MailServiceProvider::class);
         $laravel->register(ViewServiceProvider::class);
         $laravel->register(ValidationServiceProvider::class);
-
-        $settings = $laravel->make(SettingsRepositoryInterface::class);
-
-        $config->set('mail.driver', $settings->get('mail_driver'));
-        $config->set('mail.host', $settings->get('mail_host'));
-        $config->set('mail.port', $settings->get('mail_port'));
-        $config->set('mail.from.address', $settings->get('mail_from'));
-        $config->set('mail.from.name', $settings->get('forum_title'));
-        $config->set('mail.encryption', $settings->get('mail_encryption'));
-        $config->set('mail.username', $settings->get('mail_username'));
-        $config->set('mail.password', $settings->get('mail_password'));
-
         $laravel->register(DiscussionServiceProvider::class);
         $laravel->register(FormatterServiceProvider::class);
         $laravel->register(FrontendServiceProvider::class);

src/Foundation/MailServiceProvider.php

@@ -0,0 +1,79 @@
+<?php
+
+/*
+ * This file is part of Flarum.
+ *
+ * (c) Toby Zerner <toby.zerner@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Flarum\Foundation;
+
+use Flarum\Settings\SettingsRepositoryInterface;
+use Illuminate\Mail\Mailer;
+use Illuminate\Mail\Transport\LogTransport;
+use InvalidArgumentException;
+use Psr\Log\LoggerInterface;
+use Swift_Mailer;
+use Swift_SendmailTransport;
+use Swift_SmtpTransport;
+use Swift_Transport;
+
+class MailServiceProvider extends AbstractServiceProvider
+{
+    public function register()
+    {
+        $this->app->singleton('swift.mailer', function ($app) {
+            $settings = $app->make(SettingsRepositoryInterface::class);
+
+            return new Swift_Mailer(
+                $this->buildTransport($settings)
+            );
+        });
+
+        $this->app->singleton('mailer', function ($app) {
+            $mailer = new Mailer(
+                $app['view'], $app['swift.mailer'], $app['events']
+            );
+
+            if ($app->bound('queue')) {
+                $mailer->setQueue($app->make('queue'));
+            }
+
+            $settings = $app->make(SettingsRepositoryInterface::class);
+            $mailer->alwaysFrom($settings->get('mail_from'), $settings->get('forum_title'));
+
+            return $mailer;
+        });
+    }
+
+    private function buildTransport(SettingsRepositoryInterface $settings): Swift_Transport
+    {
+        switch ($settings->get('mail_driver')) {
+            case 'smtp':
+                return $this->buildSmtpTransport($settings);
+            case 'mail':
+                return new Swift_SendmailTransport;
+            case 'log':
+                return new LogTransport($this->app->make(LoggerInterface::class));
+            default:
+                throw new InvalidArgumentException('Invalid mail driver configuration');
+        }
+    }
+
+    private function buildSmtpTransport(SettingsRepositoryInterface $settings): Swift_Transport
+    {
+        $transport = new Swift_SmtpTransport(
+            $settings->get('mail_host'),
+            $settings->get('mail_port'),
+            $settings->get('mail_encryption')
+        );
+
+        $transport->setUsername($settings->get('mail_username'));
+        $transport->setPassword($settings->get('mail_password'));
+
+        return $transport;
+    }
+}