SMTP configuration

In order to have a working SMTP server we have to take care of “some” ;) points:

PTR reverse DNS record: dig +short ptr <reverse IP>.in-addr.arpa must give an hostname which DNS A record points to the <IP address> of your server.

DNS:

MX → who exchange the mail for the domain?

SPF → which addresses can be originated from the MX?

DKIM → how are signed messages outgoing from the MX?

DMARC → what actions do you suggest to mail receivers' providers regarding the conf of SPF/DKIM and where you would like to receive reports from them to tune your mail settings?

Furthermore we need working antispam and antivirus

And of course SMTP server only relay local or TLS + authenticated connections

Need to add DNS entries to the host that receives DMARC reports if domain is different from the one of the DMARC itself