Hi maurizioc92956636,
In order to make use of a new sender address, the subdomain should be delegated to Adobe (if the instance used for mail sending is hosted by Adobe). Once it has been done, tech-ops will create a mask for it inside the deployment wizard which will then allow you to use that subdomain for mail sending.
If you yourself are hosting the mail sending server, please authorize the address inside Deployment Wizard.
Reply address is something which you can keep as per your choice.
Regards,
Vipul