About ReverseMX

Each day, Internet mail servers send and receive nearly 300 billion email messages. Those servers advertise themselves as email destinations through specialized domain name records known as "MX" or "Mail eXchanger" records.

ReverseMX.com collects and analyzes these records to uncover relationships among email servers and the networks that host them.

The talented engineers at DomainTools.com built a parallel processing system that asks every domain name (in the most popular extensions) where it receives its email and which servers have permission to send email on its behalf. The team then compiled data from 90 million domains and 31 million online mail servers into specialized data structures and started building aggregations.

Here are a few interesting things we've uncovered so far:

• A vast majority of domain names, over 30 million, direct their mail to Go Daddy's servers, including one domain name that's nearly 25 years old
• Although there is a standard in place with regards to SPF Rules, 80% of the Domains that specify a mail server don't have any SPF rules defined.
• Over 300,000 Domains specify a host which resolves to localhost (127.0.0.1) as their mail server. This is used so it is not possible to send mail to any address at that domain.

The project is still in its infancy. We're anxious to hear what other ideas and connections people would like to see extracted from this data. Contact us today with your suggestions.