A server attempting to send E-mail which does not have a reverse DNS (PTR) record assigned to it is a misconfiguration. Many mail servers, including our own as well as many large systems such as AOL, do not accept mail from servers lacking reverse DNS records in order to prevent spam (according to our own logs, over 95% of all mail coming from servers without reverse DNS records is spam). An equally bad, though less common misconfiguration, is to have a PTR record that does not match or have a corresponding A record.
Thus, if your E-mail server does not have a PTR record assigned to it's IP address, or the PTR does not have a matching A record, you will receive a bounce message directing you to this page. To correct this issue, which will help ensure that your E-mail is received by anybody you attempt to send mail to, simply ask your network administrator (if you're a large company) or internet service provider to add a PTR record for your mail server's IP address. There is a tool to check your mail server's IP address for a reverse DNS record at dnsstuff.com (middle column, second one down). Please also be sure that the name your PTR record returns has a corresponding A record that resolves to the same IP address.
While you're at it, you may wish to consult DNS Report to see if there are any other outstanding DNS issues with your domain. A clean and standards-compliant setup will ensure that your internet systems interoperate with all other servers easier. If you require assistance, please feel free to contact us by telephone at 206-381-2800, or by E-mail at postmaster@seattleserver.com (mail to this accounts is not subject to the restriction) for help. We are also happy to add a temporary exemption for your mail servers if necessary, however prefer to only do this as a temporary measure while you get the problem corrected.
RFC1912 section 2.1 says you should have a reverse DNS for all your mail servers. It is strongly urged that you have them, as many mailservers will not accept mail from mailservers with no reverse DNS entry:
"Every Internet-reachable host should have a name. The consequences of this are becoming more and more obvious. Many services available on the Internet will not talk to you if you aren't correctly registered in the DNS.
Make sure your PTR and A records match. For every IP address, there should be a matching PTR record in the in-addr.arpa domain. If a host is multi-homed, (more than one IP address) make sure that all IP addresses have a corresponding PTR record (not just the first one). Failure to have matching PTR and A records can cause loss of Internet services similar to not being registered in the DNS at all. Also, PTR records must point back to a valid A record, not a alias defined by a CNAME. It is highly recommended that you use some software which automates this checking, or generate your DNS data from a database which automatically creates consistent data."
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