Sorry alessio, I would not say stupidity, but I think the solution you gave me is not correct. My problem is that I can not send from domain configured with smarthost (libero.it) to other xxxxx@libero.it accounts that are not present on Nethserver but exist on the provider.
I believe your indications refer to incoming mail where through pop3 connector I have no problem, I’m confused. If I try to send to any domain (eg gmail, I have no problem, it is as if nethserver “only fish in its db users” I would like to search on @ libero.it (provider) I remain convinced that Whether it’s dns, or something.