Habeas has announced SenderIndex, a database of e-mail sender reputations that the company will make freely available.

A collection of information on more than 60 million IP addresses and domains, SenderIndex will be available at the end of June and will be designed to help ISPs and makers of e-mail security products augment their spam-fighting efforts with additional information, said J.F. Sullivan, Habeas vice president of marketing.

Habeas has developed its own reputation engine - a set of automated tests that determine the reputation of an e-mail sender, based on 64 different criteria, and assign them to one of three categories, or lists.

The Habeas SafeList is for IP addresses that pass all Habeas tests as well as the company's e-mail accreditation program, that ensures senders are mailing legitimate messages. The company recommends that ISPs and spam filters allow messages from accredited sources to be delivered directly to the recipient's inbox.

The Habeas AcceptList is for IP addresses that have passed the Habeas tests and are deemed "not bad" senders, meaning they are not sending spam or phishing attacks, but they haven't passed the accreditation program. For messages coming from senders on this list, Habeas recommends they be scanned by spam filters before delivering to the recipient.

The third category is the BlockList, for senders who fail most of Habeas' tests. The company recommends e-mail from these senders be blocked, or connections from them throttled back.

Reputation services are already widely available; e-mail security vendors including IronPort and CipherTrust track senders by examining patterns found in the inbound mail streams their e-mail security appliances carry. Yet these systems are different from SenderIndex because they look only for negative information; in other words, they can tell users which senders are bad, but they can't guarantee that the other senders are good, explained Sullivan.

SenderIndex's information about good senders complements reputation services from other vendors, he continued, adding: "The combination of the different technologies together gives you the complete picture."

Habeas is making SenderIndex available to others for free in the hope that companies that collect information regarding e-mail senders will share their data as well, said Sullivan. SenderIndex will also act as a lead-generation tool for Habeas, he says, since the company is building up a network of good senders and can then attempt to sell its accreditation services to that list.

Sullivan pointed out that security vendor Sophos is testing SenderIndex with its e-mail security products.