System and method of electronic mail filtering using interconnected nodes

摘要

A system and method for filtering electronic mail messages is described. A message is received an processed through a one or more filter flows. Each filter flow is comprised of one or more self-contained nodes which can be combined in whatever order is required to enforce a given security policy. Node independence provides a policy-neutral environment for constructing filter flows. A filter flow may be as simple as forwarding the mail to the intended recipient, or may perform one or more checks where it decides whether to forward, reject, return (or some combination thereof) the message. Certain node types are also able to append information on to a mail message, while others are able to modify certain parts of a mail message. Several of the node types are able to generate audit or log messages in concert with processing a mail message.