Email sending not working

[jomagalo]

I am trying to send emails on the local network and I am not able to make it work. I have installed mailutils and postfix and I have configured it in a thousand ways and the emails do not reach other computers on the local network.

I have also tried configuring postfix as a relay and it always throws the same error.
delivery temporarily suspended: Host or domain name not found. Name service error for name=smtp.ionos.es type=A: Host not found, try again

delivery temporarily suspended: Host or domain name not found. Name service error for name=smtp.ionos.es type=AAAA: Host not found, try again

A or AAA appears depending on the protocol, configure postfix ipv4 or all