In your config/mail.php add this:
return [ // ..
'swisscom_mail_api' => [
'transport' => 'swisscom_mail_api',
'api_key_map' => [
config("emails.from_one") => env('MAIL_MESSAGING_API_KEY_FROM_ONE'),
config("emails.from_two") => env('MAIL_MESSAGING_API_KEY_FROM_TWO'),
],