If I have a DE and is properly linked using SubscriberKey, when try to send a test, it says success but is not sent.

So there's no way to create a test if I have not added manually this email as an opted in Subscriber, corrrect?

That's what I understood : <https://help.salesforce.com/articleView?id=mc_es_send_preview.htm&type=5>

I would like to this test email is being added automatically to the "All Subscribers" but seems that's not possible. Only when is a real sent then is added.