What is Reverse
DNS? How do I verify my Reverse DNS Settings?
In layman's terms,
you can think of a Reverse DNS (RDNS) entry in your
name server as an IP address that points back to a
domain name. When you browse a web site using
a domain name, your browser performs a Forward DNS
lookup to resolve the domain name to an IP address.
Reverse DNS is the exact opposite where you take the
IP Address and see what domain is specified for that
Many Internet service providers and email providers,
such as AOL and Hotmail, attempt to block spam by
using reverse DNS lookups on incoming email.
They do this because spammers often try to hide
their identity whereas reverse DNS is a way of
providing your identity to help indicate you are not
How can I determine what IP Address and Domain Name
is displayed in my email headers?
The easiest way to
determine what IP address and Domain Name your
eNewsletter Pro email marketing software is using is
to send yourself an email from eNewsletter Pro then
view the headers. If you are using Outlook you
can view the headers by right clicking the message
and choosing Message Options. The following
In this example, the
FQDN is Junto.adcomplete.org and the IP address is
184.108.40.206. In this example, for the
Reverse DNS to be correct, the IP Address of
220.127.116.11 must resolve back to
How can I
determine what domain name my IP address resolves
To determine if
your IP Address resolves back correctly to the
domain name, there are many tools on the internet
that you can use. One example is:
AOL Reverse DNS Tool
To use the Tool, enter
your IP Address found in the email headers:
If RDNS is setup
properly, AOL will display a success message.
However, this only indicates that they found a
reverse DNS record. You must then verify that
this matches the FQDN found in your email headers.
How can I change the
Fully Qualified Domain Name that eNewsletter Pro
utilizes in the email headers?
By default, SMTP
Express uses the base IP address of the server, and
the Fully Qualified Domain Name of the computer.
If the computer does not have a valid FQDN, or you
wish to use a different one, you can modify the
server registry settings to change the FQDN that
appears in the email headers. To do so, follow
the instructions at the link below.
How do I change the Fully Qualified Domain Name
(FQDN) used by Quicksoft SMTP Express?
If you wish to modify the server's FQDN, please see