Sender Reputation in a Large Webmail Service

In this paper, we describe how a large webmail service uses reputation to classify authenticated sending domains as either spammy or not spammy. Both SPF and DomainKey authentication are used to identify who the sender of the mail is. We describe a simple formula for how we calculate the reputation and how it is used to classify incoming mail. We show in general how domains, both good and bad, get distributed among the various reputation values, and also show the reputation values for a few specific domains. We describe some of the problems associated with this reputation system, and propose some recommendations for senders to avoid those problems.

• Type: Conference
• Year: 2006
• Where: CEAS
• Authors: Bradley Taylor
• Keywords: Authenticated Sending Domains, CEAS 2006, Internet Technology, Reputation Values, Service Uses Reputation