Using SMTP Mail Queues with Config Values in Database

Hi all!

I have been building a site on Laravel 12.x with various "system settings" stored in a custom database table - settings such as the SMTP host, port, encryption, auth username and auth password values.

I have a method in a controller that, when a particular request comes in, it will load those config values, setup the config state with those settings, and then send the SMTP mail successfully.

I am now trying to move the Mail::send command over to using Mail::queue to improve the responsiveness of the site, but I can't figure out how to get the database config to apply to messages when they are sent by the queue worker. When I have the queue worker running and then queue the message, it appears to try to load the config/mail.php config for the smtp mailer, but that only takes values from the .env file which I am not using.

On another thread, I did find mention of the Mail::build method to try to set the config into the message. However when I use that I then get errors in laravel.log sawing Mailer [ondemand] is not defined

 Mail::build([
    'transport' => 'smtp',
    'host' => $mailHost,
    'port' => $mailPort,
    'encryption' => $mailEncryption,
    'username' => $mailUsername,
    'password' => $mailPassword,
    'from' => [
        'address' => $mailFrom,
        'name' => $mailFromDisplayName
    ]
])->to( Auth::user() )->queue(new TestEmail);

[2025-04-10 10:17:07] testing.ERROR: Mailer [ondemand] is not defined. {"exception":"[object] (InvalidArgumentException(code: 0): Mailer [ondemand] is not defined. at /path/to/project/vendor/laravel/framework/src/Illuminate/Mail/MailManager.php:116)

So my question is how can I get the SMTP config loaded from the database to apply to emails sent by the queue worker? Again, it works OK when I load the config and send inside my controller, but not if I queue the messages.