Hello,
I get the following connections in mail.log today (hundreds of connections). It is probably a spammer trying to send an email. But what is the reason for the warning ? Is it because of the wrong DNS configuration of the sender: multacom ? Or a DNS Spoofing ? When I did "nslookup 74-115-52-198-dedicated.multacom.com", I got a different IP address: 204.13.152.7.
Jun 23 22:11:50 mx postfix/smtpd[20166]: connect from unknown[198.52.115.74]
Jun 23 22:11:50 mx postfix/smtpd[20166]: lost connection after UNKNOWN from unknown[198.52.115.74]
Jun 23 22:11:50 mx postfix/smtpd[20166]: disconnect from unknown[198.52.115.74]
Jun 23 22:11:50 mx postfix/smtpd[20166]: warning: 198.52.115.74: address not listed for hostname 74-115-52-198-dedicated.multacom.com