Email filtering using recipient reputation
View Patent ↗The present invention is an adaptive method for filtering spam by using the reputations associated with recipients of email messages to determine the reputations of message and content attributes, then using the attribute reputations to determine whether or not the email message is spam and then using the determination of spam to update the reputations associated with the recipients of the email message. The present invention can also be used in conjunction with existing spam algorithms. Optionally, training of existing spam algorithms may be implemented by the use of recipient reputations or training types derived from recipient reputations.
1. A method for determining whether an incoming email message entering an email system with a plurality of recipients addressed to one or more of the recipients is ham or spam comprising:
accumulating counts of unsolicited ham email messages and unsolicited spam email messages received by each recipient;
calculating recipient reputations for recipients of email messages using the accumulated counts;
calculating a sender reputation for a sender of an email message by combining the recipient reputations of the recipients associated with the sender;
calculating a message score for the email message using the calculations; and
updating the accumulated counts using the message score.
2. The method of claim 1 further comprising wherein the recipient reputations are likelihood ratios calculated from a ratio of the unsolicited ham email messages to the unsolicited spam email messages received by each recipient.
3. The method of claim 1 further comprising calculating the message score using the sender reputation.
4. The method of claim 1 further comprising calculating an IP reputation for an IP address using a ratio of good to bad senders sending email messages from the IP address.
5. The method of claim 4 further comprising calculating the message score using the IP reputation.
6. The method of claim 4 further comprising calculating the message score for the email message using the sender reputation and the IP reputation.
7. The method of claim 1 further comprising storing sender reputations and IP reputations at a central network location.