System and method of filtering unwanted electronic mail messages

• US 20050044154A1
• Filed: 08/10/2004
• Published: 02/24/2005
• Est. Priority Date: 08/22/2003
• Status: Abandoned Application

• Current Assignee: Centura Software Corp.
• Original Assignee: Centura Software Corp.
• Inventors: Kaminski, David, Strange, Reggie
• Application Number:
  US10/915,291
• Publication Number:
  US 20050044154A1
• Time in Patent Office: Days
• US Class Current: 709/206
• CPC Class Codes: H04L 51/212 using filtering or selective blocking

Abstract

An anti-spamming agent filters incoming email messages to eliminate unsolicited and unwanted email messages, particularly bulk email messages commonly known as spam. The anti-spamming agent gives all incoming mail messages a score and processes the messages based on the message score. Messages receiving a qualifying score are forwarded to the user. All other messages are either discarded or quarantined while the anti-spamming agent performs further authorization procedures, such as a challenge-response procedure. When a message from an unknown sender is received, a verified mail registry may be queried to authenticate the sender, and the mail may be processed based on the response from the verified mail registry.

Claims

1. A method of filtering unwanted electronic mail messages comprising:

receiving electronic mail messages;

assigning a message score to the electronic mail messages;

filtering the electronic mail messages based on the assigned score by;

forwarding the electronic mail messages that receive a qualifying score;

quarantining at least some of the electronic mail messages that fail to receive a qualifying score; and

sending a challenge to senders of the quarantined electronic mail messages.

2. The method of claim 1 further comprising deleting electronic mail messages that receive a disqualifying score, wherein the electronic mail messages receiving a message score between the qualifying and disqualifying scores are quarantined.

3. The method of claim 1 further comprising revising the message score assigned to the quarantined electronic mail messages based on the senders'"'"' responses to the challenge.

4. The method of claim 3 further comprising forwarding quarantined electronic mail messages that receive a qualifying score after revision.

5. The method of claim 3 further comprising deleting quarantined electronic mail messages that receive a disqualifying score after revision.

6. The method of claim 3 further comprising deleting quarantined electronic mail messages that fail to receive a qualifying score after a predetermined time period.

7. The method of claim 1 further comprising retaining the quarantined electronic mail messages for a predetermined period and deleting the quarantined messages after expiration of the determined time period.

8. The method of claim 1 wherein assigning a message score to the electronic mail message comprises:

determining a source address associated with the electronic mail message;

assigning a message score to the electronic mail message based on the source address.

9. The method of claim 8 wherein assigning a message score to the electronic mail message based on the source address comprises identifying the sender of the electronic mail message based on the source address and assigning a score to the electronic mail message based on the identity of the sender.

10. The method of claim 9 further comprising maintaining a sender database containing identifying information associated with senders of electronic mail messages, and sender scores correlated with the identifying information.

11. The method of claim 10 wherein assigning a score to the electronic mail message based on the identity of the sender comprises assigning message scores to the electronic mail messages based on the sender scores stored in the sender database.

12. The method of claim 11 further comprising revising sender scores responsive to electronic mail messages that receive a qualifying score.

13. The method of claim 12 wherein sender scores are increased responsive to electronic mail messages that receive a qualifying score.

14. The method of claim 11 further comprising revising sender scores responsive to electronic mail messages that fail to receive a qualifying score.

15. The method of claim 14 wherein sender scores are decreased responsive to electronic mail messages that fail to receive a qualifying score.

16. The method of claim 8 wherein assigning a message score to the electronic mail message based on the source address comprises identifying the domain of the source address and assigning a score based on the domain.

17. The method of claim 8 wherein assigning a message score to the electronic mail message based on the source address comprises comparing the source address to one or more patterns and assigning a score to the electronic mail message based on the pattern if a matching pattern is found.

18. The method of claim 8 wherein assigning a message score to the electronic mail messages comprises examining the contents of the electronic mail message and assigning a score to the electronic mail message based on the contents.

19. A method of preventing looping in a network used to deliver electronic mail messages, comprising:

receiving an electronic mail message for a designated recipient from an unauthorized sender, said message containing an authorization code;

quarantining the electronic mail message; and

generating a challenge containing the authorization code and sending the challenge to the originator of the electronic mail message;

20. The method of claim 19 wherein the electronic mail message includes a header containing the authorization code.

21. The method of claim 20 wherein the challenge includes a header containing the authorization code.

22. The method of claim 19 further comprising receiving a reply from the unauthorized sender and forwarding the original electronic mail message if the reply is acceptable.

23. A method of preventing looping in a network used to deliver electronic mail messages, comprising:

forwarding an electronic mail message from an originator to a mail server for a designated recipient, said electronic mail message containing an authorization code; and

receiving a challenge from the mail server for the designated recipient containing the authorization code; and

forwarding the challenge to the originator of the original electronic mail message.

24. A method of preventing message looping in a network used to deliver electronic mail messages, comprising:

inserting a loop prevention code into an outgoing mail electronic mail message from a sender to a designated recipient;

wherein the loop prevention code in a reply message intended for the sender indicates to a mail server for the sender that the reply message should be forwarded to the sender.

25. The method of claim 24 wherein the loop prevention code is inserted into a header portion of the electronic mail message.

26. A computer system for filtering unwanted electronic mail messages comprising:

a filter module to score incoming electronic mail messages;

an isolation queue to quarantine at least some electronic mail messages that fail to receive a qualifying score;

a challenge module to challenge the senders of the quarantined electronic mail messages.

27. The computer system of claim 26 wherein the filter module deletes electronic mail messages that receive a disqualifying score, wherein the electronic mail messages receiving a message score between the qualifying and disqualifying scores are quarantined.

28. The computer system of claim 26 further comprising a queue manager to manage quarantined mail messages, wherein the queue manager is operative to:

revise the message score assigned to a quarantined electronic mail message based on the senders'"'"' responses to the challenge by the challenge module; and

forward quarantined electronic mail messages that receive a qualifying score after revision.

29. The computer system of claim 28 wherein the queue manager deletes quarantined electronic mail messages that fail to receive a qualifying score after a predetermined time period.

30. The computer system of claim 26 wherein the filter module assigns a message score to the electronic mail message based on the source address.

31. The computer system of claim 30 wherein the filter module assigns a message score to the electronic mail message by identifying the sender of the electronic mail message based on the source address, and assigning a score to the electronic mail message based on the identity of the sender.

32. The computer system of claim 31 further comprises a sender database containing addresses associated with senders of electronic mail messages, and sender scores correlated with the addresses for use in scoring incoming mail messages.

33. The computer system of claim 32 further including a scoring module to update sender scores in the scoring database responsive to predetermined events.

34. The computer system of claim 33 wherein the scoring module updates sender scores when mail messages are delivered.

35. The computer system of claim 33 wherein the scoring module updates sender scores when mail messages are discarded or deleted.

36. The computer system of claim 30 wherein the filter module assigns a message score to the electronic mail message by identifying the domain of the source address, and assigning a score based on the domain.

37. The computer system of claim 30 wherein the filter module assigns a message score to the electronic mail message by comparing the source address to one or more patterns and assigning a score to the electronic mail message based on the pattern if a matching pattern is found.

38. The computer system of claim 30 wherein the filter module assigns a message score to the electronic mail messages by examining the contents of the electronic mail message and assigning a score to the electronic mail message based on the contents of the electronic mail message.

39. An electronic mail system to prevent looping in a network used to deliver electronic mail messages, comprising:

a computer having a processor and a memory;

a mail server application stored in memory and executed by said processor, said mail server application including code to;

receive an electronic mail message for a designated recipient from an unauthorized sender, said message containing an authorization code;

quarantine the electronic mail message; and

generate a challenge containing the authorization code and sending the challenge to the originator of the electronic mail message;

40. The electronic mail system of claim 39 wherein the electronic mail message includes a header containing the authorization code.

41. The electronic mail system of claim 39 wherein the challenge includes a header containing the authorization code.

42. The electronic mail system of claim 39 wherein the mail server application further includes code to process a reply from the unauthorized sender and to forward the original electronic mail message if the reply is acceptable.

43. An electronic mail system to prevent looping in a network used to deliver electronic mail messages, comprising:

a computer having a processor and a memory;

a mail server application stored in memory and executed by said processor, said mail server application including code to;

forward an electronic mail message from an originator to a mail server for a designated recipient, said electronic mail message containing an authorization code; and

receive a challenge from the mail server for the designated recipient containing the authorization code; and

forward the challenge to the originator of the original electronic mail message.

44. An electronic mail system to prevent message looping in a network used to deliver electronic mail messages, comprising:

a computer having a processor and a memory;

a mail client application stored in memory and executed by said processor, said mail client application including code to insert a loop prevention code into an outgoing mail electronic mail message from a sender to a designated recipient wherein the loop prevention code in a reply message intended for the sender indicates to a mail server for the sender that the reply message should be forwarded to the sender.

45. The electronic mail system of claim 44 wherein the loop prevention code is inserted into a header portion of the electronic mail message.

46. A mail server application stored in a computer readable medium for filtering unwanted electronic mail messages comprising code to:

receive incoming electronic mail messages;

assign a message score to incoming electronic mail messages;

filter the incoming electronic mail messages based on the assigned score;

forward the electronic mail messages that receive a qualifying score;

quarantine at least some of the electronic mail messages that fail to receive a qualifying score; and

send a challenge to message senders of the quarantined electronic mail messages.

47. The mail server application of claim 46 wherein the mail server application further includes code to revise the message score of quarantined messages based on a response by the message sender to the challenge.

48. The mail server application of claim 47 wherein the mail server application further includes code to forward quarantined messages that receive a qualifying score before expiration of a predetermined time period.

49. The mail server application of claim 47 wherein the mail server application further includes code to delete quarantined messages that fail to receive a qualifying score before expiration of a predetermined time period.

50. The mail server application of claim 46 wherein the mail server application further includes code to delete incoming mail messages that receive a disqualifying score.

51. A mail server application stored in a computer readable medium comprising code to:

receive an electronic mail message for a designated recipient from an unauthorized sender, said message containing an authorization code;

quarantine the electronic mail message; and

generate a challenge containing the authorization code and send the challenge to the originator of the electronic mail message;

52. A mail server application stored in a computer readable medium comprising code to:

forward an electronic mail message from an originator to a mail server for a designated recipient, said electronic mail message containing an authorization code;

receive a challenge from the mail server for the designated recipient containing the authorization code; and

forward the challenge to the originator of the original electronic mail message.

53. A mail client application stored in a computer readable medium comprising code to insert a loop prevention code into an outgoing mail electronic mail message from a sender to a designated recipient wherein the loop prevention code in a reply message intended for the sender indicates to a mail server for the sender that the reply message should be forwarded to the sender.