Mail on Postfix, how to organize?

Question

linux

So 2 weeks of my studying linux have passed and I got to the mail server ... actually the question is as follows:
How to organize your mail server? that is, I know how to install postfix and dovecot, but there are a few doubts in the settings ...
the question is this: I want to configure my mail server so that I can send to mailboxes on the Internet, that is, not local, .... what do I need for this need? find a free domain, register and then just enter it in the postfix settings, or do you need to configure something else on this domain? help a newbie, the question is exactly how and where, for example, found a free domain, and then what???

Answer 1

Googling further on the subject of Postfix + Dovecot settings. In 2 words, this is not described - read the documentation and articles. Example set. Then ask questions if you don't understand something.

Answer 2

after setting up, pass the test on open relay. services that check for openings on the Internet in bulk.
see https://4admin.info/system-administration-unix/ - Mail section