Your best bet is to register your own domain. Preferably with an unrestricted generic TLD like .com or .net as you may lose the right for a specific TLD at some

Your best bet is to register your own domain. Preferably with an unrestricted generic TLD like .com or .net as you may lose the right for a specific TLD at some point, for example if you are using your country TLD and you move. What is less certain is: will the service still work and will the email pass the spam filters?