But the system allways want to send mails via swiftmailer. I seen in base/Application.php that swiftmailer is configured at standard mailer. But i thought the standard configuration will overwrite with the config in web.php.
Please note that the sample configuration in the docs is incorrect. You might need to remove the ‘dsn’ element from the first transport config sample: 'dsn' => 'native://default',
That will cause the other settings to be ignored. You can only use one or the other.
There are several issues with the current version of the symfonymailer extension.
There is a new version waiting for the 3.0 release of the extension, you can try that one if you want: