IP Global E-mail Policy : No Reverse DNS

If you have received an e-mail with a pointer to this web page then you have attempted to send an e-mail message from a mail server with an IP address that is improperly configured for a reverse DNS entry. This E-mail policy has been implemented in order to verify the identity of the source mail server. If you are responsible for making these configuration changes, please correct this problem immediately. If you are not responsible for these matters, please contact your Internet Service Provider or E-mail Provider in order to resolve your issue.

Brief Explanation

Upon receiving an inbound e-mail message from a mail server, IP Global performs a reverse lookup on the source IP address and one of the following occured: There was no PTR record associated with the IP address The DNS server authoritative for the DNS of the originating IP block is misconfigured

Detailed Explanation

In order to communicate on the Internet, a device must be identified by a publically routable IP address. An IP address (eg. 11.22.33.44) is a number that is assigned to each node, whether it is a mail server, a web server, or your own personal desktop so that when you try to access other nodes on the Internet a common path can be determined allowing communication to take place. Generally, you will not deal with the actual IP address of the node hosting the service you wish to access; you deal with the DNS name (i.e. host, hostname, etc.). The DNS name allows end users to associate an easy to remember identifier with the IP address, e.g. www.ipglobal.net, is much easier to remember than the number string of four octets. When you enter a website into your browser, the browser translates the name into the IP address much like telephone voice recognition service translates a name to a telephone number. Once this "translation" has occured, your machine may continue the communication process. This is what is known as a Forward DNS Lookup. A Reverse DNS Lookup is implemented in the opposite way, in that it "translates" an IP address to a DNS name. This is sometimes necessary so that the host name and originating source can be verified. All IP addresses that are utilized on the Internet should possess a Reverse DNS Entry (PTR Record). Refer to the following example for more information: Example. DNS Name: www.juniper.net Forward DNS Lookup: # nslookup www.juniper.net Name: www.juniper.net Address: 207.17.137.68 Reverse DNS Lookup: # nslookup 207.17.137.68 Name: juniper.net Address: 207.17.137.68 There is a lot of information that can be determined from an IP address in most instances. It is possible to associate an IP address with a geographical location, the upstream providers, technical contact name for responsible parties, and even the type of machine as well as services that are hosted. The IP address used that directed you to this page attempted to access an IP Global server and was denied access because it did not have a valid reverse DNS (PTR) record associated with it. It is the responsibility of the person or organization that maintains the authoritative zone to resolve the issue that you are experiencing.