IPAddressToDomain SharedMX

From Paterva Wiki

This transform queries two 'historical' DNS providers (Serversniff and Robtex) to determine if this IP address is the also used by other domains as an MX record. This type of 'reverse MX lookup' cannot be performed using standard DNS queries and is very useful to find other domains associated with the IP number. In most cases one would work from the actual DNS name of the MX record, but if you only have the IP address available there is no standard way of knowing if the IP address is an MX for a domain or not. This transform gives you the ability to do this.