Cleaning up a bad email reputation

...mail from their customers if they are confident that the businesses sending that mail are doing the right things."

There is some uniformity in establishing email reputation scores, said George Bilbrey, general manager at ReturnPath. Typically, the score is based on six factors: complaints, percentage of mail sent to nonexistent addresses, number of mail hitting spam traps, response to unsubscribe requests, sending infrastructure and mail volume, he said.

The reputation will be attached to the sender's domain or IP address. Reputation systems may weigh the components differently, depending on their place in the email chain. A spam-filtering appliance or hosted service may give more weight to email volume and patterns, while for an email service provider, the customer complaint rate might be most important.

"Users are voting with their mouse on reputation," said Craig Spiezle, a director at Microsoft, which operates the Hotmail Web email service. "We think that is the best way. It is really in the eyes of the in-box user what is relevant."

But some are troubled by the notion that something set by others — their reputation — can be decisive in whether their email gets delivered. Nicole Hampton, a station production manager at Cox Radio Interactive, worries about the business's reputation being hurt by miscreants abusing Web site mailing features, for example, she said.

Zombies, or computers controlled by outside hackers, pose another threat. An organisation could have its systems commandeered and used to send out spam email. This ultimately could affect a company's legitimate email, which may end up being blocked by spam filters, noted Michael Osterman, the head of Osterman Research, which focuses on Internet messaging.

"Reputation filtering is an important component of overall messaging management, but it needs to be combined with other tools to fully protect a network," he said.

Such a hijack of a company's email system is possible, but it probably wouldn't hurt its reputation immediately, Spiezle said, noting that a reputation is established over time.

Checking up
For companies curious about their email reputation, Habeas and ReturnPath both plan to launch online services that will give them some insight into it. Beyond that, Habeas charges $2,500 (£1,400) for a more in-depth diagnosis, and ReturnPath consultants can be hired for $5,000 a month to work with a business and make sure its mail is delivered.

Spam-filtering specialist CipherTrust already offers a Web site, called TrustedSource, that gives some details about its reputation-ranking system. In addition, large email service providers, such as Hotmail, provide a "feedback loop", which lets message senders see the opinion recipients have of them.

One thing that email service providers are looking at is whether it makes sense to share reputation data among ISPs, Microsoft's Spiezle said. Ultimately, he said, providers such as AOL, Yahoo and Microsoft are going to make decisions based on what their users tell them. But pooling information could make reputation data more reliable.

"Sharing best practices and sharing reputation data among major ISPs is some of the discussion that is going on today," Spiezle said.