List Description

RATS-NoPtr is a collection of IP Addresses that have been detected sending an abusive amount of connections, or trying to send to too many invalid users at ISP and Telco's mail servers. A distinguishing characteristic is that the IP lacks a reverse DNS/PTR record. IPs running mail servers should always have a proper reverse DNS record.

List Specifications

You should ONLY need to remove yourself from this list IF you are running your own mail server.

Real mail servers should have a reverse DNS/PTR record that reflects the operators of the mail server, according to Best Practices for Email and Network Operators. The reverse DNS of an IP running a mail server should reflect who the responsible party is, with the responsible party being the one who is responsible for managing that mail server.

For example:
-- or --

Rats-NoPtr contains IPs on networks that are known to allow egress on port 25 from IPs that do not have a reverse DNS record. If an IP does not have a reverse DNS and if it is sending a flood of connections, you can be sure it is an infected machine or improperly configured mail server. This type of activity represents approximately 50% of all wasted overhead facing mail servers.

Download / Install

If you are interested in querying RATS-NoPtr, you can query it just like any other RBL using the hostname "". If you need more information or assistance, please feel free to contact us. We also recommend that you refer to our Terms of Service to check if you qualify for free usage.


As mentioned above, you can only remove your IP address from this list if you have corrected the reverse DNS to better conform to "Best Practices for Email and Network Operators". Please ensure that enough time has passed for DNS propagation. If you are unable to remove yourself please contact us through our contact form about this case.

Enter the IP Address you wish to remove:

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