| When one first tackles the project of getting | | | | reverse or PTR record, simply enter |
| Internet mail delivered to their mail system, you | | | | ptr:IPAddress in the command box, where |
| are very quickly pointed to the need for getting | | | | IPAddress is your server's public IP address. If the |
| an MX record published within your domain's public | | | | results of these queries are consistent, you are all |
| DNS zone. It is this record that tells all of the | | | | set. If not, don't fret; the fix is not difficult. |
| other mail servers on the planet where to route | | | | Getting the forward (A record) entry published in |
| email destined for your domain. | | | | DNS is no different than publishing any other |
| What most do not tell you is the importance of | | | | address. You simply work with your DNS hosting |
| getting both the forward (A record) and reverse | | | | provider to publish the name you have setup for |
| (PTR record) DNS entries right for the server | | | | your send connector just like you did when you |
| that is the send connector. In some cases this is | | | | added your MX record or published the WWW |
| the same server as the receive connector, but it | | | | address for your domain by providing them with |
| does not need to be. It is very important that | | | | the full name and apparent IP address. It is the |
| any server that is configured as an Internet Send | | | | reverse entry or PTR record that is a bit tricky. |
| Connector have both a forward (A record) and | | | | This is because you cannot directly publish your |
| reverse (PTR record) published in DNS, and that | | | | own PTR record as you are most likely not the |
| these records exactly match what you have | | | | owner of the IP block your organization is using; |
| entered in the FQDN field on the general tab of | | | | your ISP is. You simply need to work with your |
| your Send Connector. If this one server is hosting | | | | ISP to publish the reverse entry. This is a |
| both the send and receive connectors, the MX | | | | common request and many of the larger ISPs |
| record should also point to this same name. If | | | | have even added this functionality to their |
| your organization accepts mail for more than one | | | | customer self-help portals. This approach only |
| domain, simply point the MX record in each | | | | works though if you have a static IP address |
| domain to the same FQDN. There is no | | | | range from your ISP. |
| requirement that an MX record point to a server | | | | If your Internet service is being issued a |
| in the same DNS domain as the MX record. | | | | dynamic address, this above approach will not |
| You may be thinking, "Why is it so important that | | | | work. Assuming that you need to make sure |
| all of these names match?"... The underlying | | | | your mail is delivered; you will then have a choice |
| reason is that mismatched entries and a lack of a | | | | to make. You can either change your ISP service |
| reverse DNS entry are used by most Anti-Spam | | | | to one with a Static IP range and follow the |
| services as a signal that mail messages from this | | | | instructions above, or use a "Smarthost". A |
| host should be treated as Spam. Some | | | | Smarthost is simply another server or servers on |
| organizations, such as AOL and Comcast, go as | | | | the Internet that "Trusts you". This is usually a |
| far as to outright block mail from hosts that do | | | | paid service where they provide you with a |
| not have a matching reverse DNS entry. If your | | | | username/password combination to authenticate |
| organization's email is to get delivered, you need | | | | your mail server regardless of the IP address it is |
| to do everything you can to lower the suspicions | | | | using at the time. It is these servers that then |
| of the Anti-Spam services. | | | | deliver your mail messages to their ultimate |
| You can check your organization's DNS entries | | | | destination. Your ISP will often provide this |
| quickly and easily using the tools at To look for | | | | service, so start with them 1st. It is important |
| the forward or A record of your server, simply | | | | that you make sure that they do not provide this |
| enter a:Servername in the command box, where | | | | service for their customers as many ISPs actively |
| Servername is the fully qualified domain name of | | | | block SMTP (email) traffic from their entire |
| your server as entered in the FQDN of your | | | | dynamic IP service range to keep themselves on |
| Send Connector within Exchange. To look for the | | | | good standing. |