Every day, I receive several warnings similar to these in my /var/log/maillog file. My mail configuration seems to be functioning correctly, but I'm not quite sure what these warnings mean. Code: Aug 31 00:01:03 webserver postfix/smtpd[7827]: warning: 201.104.49.21: hostname dup-201-104-49-21.prod-dial.com.mx verification failed: Name or service not known Aug 31 00:36:54 webserver postfix/smtpd[8714]: warning: 201.160.212.96: hostname 201.160.212.96.cableonline.com.mx verification failed: Name or service not known Aug 31 01:44:53 webserver postfix/smtpd[9840]: warning: 200.106.107.20: hostname client-200.106.107.20.speedy.net.pe verification failed: Name or service not known Aug 31 02:26:42 webserver postfix/smtpd[10485]: warning: 74.133.61.83: hostname DHCP-74-133-61-83.insightbb.com verification failed: Name or service not known Aug 31 03:36:56 webserver postfix/smtpd[11578]: warning: 72.9.4.21: hostname d-72-9-4-21.metrocast.net verification failed: Name or service not known Can anyone tell me what these warnings mean, or how to fix it??? zalo
This means that postfix is not able to verify (lookup) the hostnames mentioned in the DNS system. This normally means that they do not exist. This is nothing to worry about, they normally appear when spam arrives from a host that is not listed in DNS.
Thanks for a fast reply, Then it is propabbly generated when when spam arrives. Because the domain name that is in the log is not one of my domains
