Cisco Cisco Email Security Appliance X1050 Troubleshooting Guide
What does the log message "verified no" mean?
Document ID: 118173
Contributed by Stephan Fiebrandt and Tomki Camp, Cisco TAC
Engineers.
Aug 15, 2014
Engineers.
Aug 15, 2014
Contents
Introduction
Background Information
Background Information
Introduction
This document describes the meaning of "verified no" on incoming SMTP connections.
Background Information
Here is an example of a "verified no" log message:
Wed Nov 17 10:00:20 2004 Info: New SMTP ICID 353419258 interface
PublicNet(10.111.123.234) address 103.102.100.99 reverse dns
host unknown verified no
Log messages of this type indicate the following:
The IP address does not reverse resolve to a fully qualified domain name (FQDN).
1.
The hostname found from the Reverse Resolution does not Forward Resolve to the same IP address as
is connecting.
is connecting.
2.
This condition is often seen for ISPs with poorly maintained DNS records.
This condition will typically not cause mail delivery to fail.
Cisco customers can throttle or block messages from domains with DNS issues.
Updated: Aug 15, 2014
Document ID: 118173