Laravel 6 never emails - php

Question

I understand that Laravel no longer supports the mail() command that Wordpress and probably every other system use to simply send an email.
https://github.com/swiftmailer/swiftmailer/issues/866 shows that they now require smtp. Ok, but even if you sign up for a smtp service, and enter all the details as in:
https://www.bnmetrics.com/blog/sending-email-using-mailgun-laravel5
and php artisan config:cache ... repeatedly... with "smtp" or "mailgun" as the api, it never can even send the reset password built in to the Laravel user system.
Expected response code 250 but got code "530", with message "530 5.7.1 Authentication required"
What's worse is that it never changes from that error message, even if I set
MAIL_HOST=smtp.example.com
it is never a different error message. Which makes me think something is seriously wrong with Laravel Mail (other than the fact it forbids using the standard mail/sendmail that just about any proper configured server can do). Is there a way I can composer install version 5.4.4 which apparently was the last working version according to here, or is there a better way to get Laravel mail working... with or without external service smtp?

Answer 1

If php artisan config:cache doesn't work and you are using e-mails in background using Laravel queues or Horizon, you should run:
php artisan queue:restart
or
php artisan horizon:terminate
to make sure workers will see config changes. Of course you should have Supervisor configured to run those queue workers after being stopped

Answer 2

Route::get('/sometesturl', function() {
var_dump(Config::get('mail'));
echo config('mail.port');
echo config('mail.driver');
echo config('mail.username');exit;
});
shows that there was no username even. Looking in the .env file I found that the added MAIL_ vars were getting overwritten by some defaults below!