Proofpoint this week announced an e-mail reputation service for its security software and appliances that drops connections from known spammers and other questionable senders, cutting down on unwanted messages while saving valuable resources on a corporation’s network.

Available now, Proofpoint Dynamic Reputation uses a combination of predictive behavioral data and historic reputation information about a sender to determine whether they are legitimate, according to company officials. By warding off connection requests from spammers directly or from comprised PCs that spammers have taken over, the service can block more than 80% of inbound connections, with a “false positive” or mistake rate of less than one in a million, they say. It also can block directory harvest attacks, denial-of-service attacks and other e-mail threats by dropping these connections.

The service’s reputation profiles are updated every minute so that spam blasts and other events can be caught nearly immediately, the company says.

The service builds on Proofpoint’s existing connection-management features with the addition of netMLX, Proofpoint’s reputation analysis technology that uses machine learning to build a database of the sending behaviors of IP addresses. It then comes up with a score for each address so that customers can decide whether to accept, reject or slow down connections from each sender rated.

By blocking more than 80% of the connection attempts coming into an organization, Proofpoint’s service helps to reduce e-mail volume without requiring additional hardware, officials say, which has become more important as spam volumes have increased significantly over the past year.

Access to the netMLX database is priced at $3,750 per year. Proofpoint Dynamic Reputation is included with the company’s Protection Server software and e-mail security appliances.