Method and system for filtering electronic messages

Abstract

The present invention provides a system and method for filtering unsolicited electronic commercial messages. A system and method according to the present invention for screening out unsolicited commercial messages comprises the steps of receiving a message from a sender, sending a challenge back to the sender, receiving a response to the challenge, and determining if the response is a proper response.

1. A method for filtering electronic messages, the method comprising:
 receiving an electronic message from a sender, the electronic message including an address field containing a sender's address;  
 comparing the sender's address to a list of accepted senders;  
 applying a heuristic to the sender's address to determine if the sender's address is formatted according to a message standard of a messaging medium of transmission through which the electronic message is received in order to make a determination of whether the sender's address is valid or invalid;  
   analyzing the electronic message to determine whether the electronic message includes a first token that indicates that the electronic message is a reply to a first challenge message; and   
 sending a prompt  second challenge message back to the sender if the sender's address is valid and if the sender's address is not contained in the list of accepted senders and if the electronic message does not include the first token, wherein the second challenge message includes a prompt is  designed to be answered by a person and not a machine and wherein the second challenge message further includes a second token.  
 
     
     
       2. The method of  claim 1 , wherein the electronic message is an e-mail. 
     
     
       3. The method of  claim 1 , further comprising a step of determining if information regarding the sender is listed on a predetermined list, the predetermined list being defined before receiving the electronic message from the sender. 
     
     
       4. The method of  claim 1 , further comprising a step of not filtering out the message if information regarding the sender is listed on the list of accepted senders. 
     
     
       5. The method of  claim 1 , further comprising a step of comparing the sender's address to a list if  of blocked addresses and filtering out the electronic message if information regarding the sender is listed on the list of blocked addresses. 
     
     
       6. The method of  claim 1 , further comprising a step of automatically adding information regarding the sender to a  the list of accepted senders. 
     
     
       7. The method of  claim 1 , further comprising a step of determining if the received electronic message is properly addressed to a predetermined receiver  recipient. 
     
     
       8. The method of  claim 7 , wherein a  the received electronic message is filtered out if the received electronic message is not properly addressed to the predetermined receiver  recipient. 
     
     
       9. The method of  claim 1  additionally comprising a step of receiving a response to the prompt and adding the sender's address to the list of accepted senders if the response to the prompt is correct. 
     
     
       10. The method of  claim 1  additionally comprising a step of receiving a response to the prompt and adding the sender's address to a list of blocked senders if the response to the prompt is incorrect. 
     
     
       11. The method of  claim 10  additionally comprising a step of deleting the response if the response does not contain a correct answer to the prompt. 
     
     
       12. The method of  claim 11  wherein the step of deleting the response comprises moving the response to a deleted messages folder. 
     
     
       13. The method of  claim 1  wherein the sender's address field is a reply address field and the sender's address is a reply address for the sender. 
     
     
       14. The method of  claim 1 , wherein the step of  additionally comprising a step of comparing the sender's address to a list of blocked senders, wherein the step of sending a prompt  second challenge message back to the sender comprises sending a prompt  second challenge message back to the sender only if the sender's address is not in the list of accepted senders and not in the list of blocked senders  if the sender's address is valid, the sender's address is not contained in the list of accepted senders, the sender's address is not contained in the list of blocked senders and the electronic message does not include the first token. 
     
     
       15. The method of  claim 14  additionally comprising a step of deleting the message if the sender's address is in the list of blocked senders. 
     
     
       16. The method of  claim 1  additionally comprising a step of adding the sender's address to the list of accepted senders if the sender correctly responds to the prompt. 
     
     
       17. A system for filtering electronic messages, the system comprising:
 means for receiving an electronic message from a sender;    means for determining that a return address of the sender is an accepted sender's address;    means for sending a prompt back to the sender if the return address is not an accepted sender's address, wherein the prompt is designed to be answered by a person and not a machine.    
     
     
       18. The system of  claim 17 , wherein the means for determining comprises means for determining if the address is listed on a list. 
     
     
       19. The system of  claim 18 , further comprising means for not filtering out the message if information regarding the sender is listed on the list of accepted senders. 
     
     
       20. The system of  claim 18 , further comprising means for filtering out the message if information regarding the sender is listed on a list of blocked senders. 
     
     
       21. The system of  claim 17 , further comprising means for adding information regarding the sender to a list. 
     
     
       22. The system of  claim 17 , further comprising means for determining if the received message is properly addressed to a predetermined receiver. 
     
     
       23. The system of  claim 22 , wherein the received message is filtered out if it is not properly addressed to the predetermined receiver. 
     
     
       24. A non- transitory  computer readable medium containing program instructions for filtering electronic messages, the program instructions comprising:
 receiving an electronic message from a sender, the electronic message including an address field containing a sender's address;  
 comparing the sender's address to a list of accepted senders;  
 applying a heuristic to the sender's address to determine if the sender's address is formatted according to a message standard of a messaging medium of transmission through which the electronic message is received to make a determination of whether the sender's address is valid or invalid;  
   analyzing the electronic message to determine whether the electronic message includes a first token that indicates that the electronic message is a reply to a first challenge message,   
 sending a prompt  second challenge message back to the sender if the sender's address is valid and if the sender's address is not contained in the list of accepted senders and if the electronic message does not include the first token, wherein the second challenge message includes a prompt is  designed to be answered by a person and not a machine and wherein the second challenge message further includes a second token.  
 
     
     
       25. The medium of  claim 24  additionally comprising  wherein the program instructions additionally comprise a step of receiving a response to the prompt and adding the sender's address to the list of accepted senders if the response to the prompt is correct. 
     
     
       26. The medium of  claim 24  additionally comprising  wherein the program instructions additionally comprise a step of receiving a response to the prompt and adding the sender's address to a list of blocked senders if the response to the prompt is incorrect. 
     
     
       27. The medium of  claim 26  additionally comprising  wherein the program instructions additionally comprise a step of deleting the response if the response does not contain a correct answer to the prompt. 
     
     
       28. The medium of  claim 27  wherein the step of deleting the response comprises moving the response to a deleted messages folder. 
     
     
       29. The medium of  claim 24  wherein the sender's address field is a reply address field and the sender's address is a reply address for the sender. 
     
     
       30. A method for filtering electronic messages, the method comprising:
 receiving an electronic message from a sender, the message including a sender's address field containing an address of the sender;  
 comparing the sender's address to a list of accepted senders;  
 applying a heuristic to the sender's address to determine if the sender's address is formatted according to a message standard of a messaging medium of transmission through which the electronic message is received to make a determination of whether the sender's address is valid or invalid; 
 sending a challenge back to the sender if the sender's address is valid and if the sender's address is not in the list of accepted senders, wherein the challenge is designed to be answered by a person and not a machine, the challenge including a prompt and a legal notice designed to be answered by a person and not a machine.  
 
     
     
       31. The method of  claim 30 , wherein the challenge includes a prompt. 
     
     
       32. The method of  claim 30 , wherein the challenge includes a legal notice. 
     
     
       33. The method of claim  32    30 , wherein the legal notice includes text which cannot be altered once the text is sent to the sender. 
     
     
       34. The method of  claim 30 , further comprising a step of automatically updating the list of accepted senders. 
     
     
       35. The method of  claim 30 , wherein the challenge includes a program version number. 
     
     
       36. The method of  claim 30 , further comprising a step of determining if the received electronic message is properly addressed to a predetermined receiver  recipient. 
     
     
       37. The method of  claim 36 , wherein the received message is filtered out if it is not properly addressed to a predetermined receiver  recipient. 
     
     
       38. The method of  claim 1  additionally comprising:
   receiving a response to the prompt of the second challenge message; and        automatically accepting the electronic message without filtering out the electronic message, if the received response includes:      the second token; and        a correct response to the prompt of the second challenge message.       
     
     
       39. The method of  claim 1  additionally comprising:
   receiving a response to the prompt of the second challenge message; and        automatically adding the sender's address to the list of accepted senders, if the received response includes:      the second token; and        a correct response to the prompt of the second challenge message.       
     
     
       40. The method of  claim 1  additionally comprising:
   receiving a response to the prompt of the second challenge message; and        automatically adding the sender's address to a list of blocked senders, if the received response includes:      the second token; and        an incorrect response to the prompt of the second challenge message.       
     
     
       41. The method of  claim 1  additionally comprising:
   receiving a response to the prompt of the second challenge message; and        automatically deleting the electronic message, if the received response includes:      the second token; and        an incorrect response to the prompt of the second challenge message.       
     
     
       42. The method of  claim 1  wherein the second challenge message further includes a program version number. 
     
     
       43. The medium of  claim 24  wherein the second challenge message further includes a program version number. 
     
     
       44. The medium of  claim 24  wherein the electronic message is an e- mail.   
     
     
       45. The medium of  claim 24  wherein the program instructions additionally comprise a step of determining if information regarding the sender is listed on a predetermined list, the predetermined list being defined before receiving the electronic message from the sender. 
     
     
       46. The medium of  claim 24  wherein the program instructions additionally comprise a step of not filtering out the message if information regarding the sender is listed on the list of accepted senders. 
     
     
       47. The medium of  claim 24  wherein the program instructions additionally comprise a step of comparing the sender's address to a list of blocked addresses and filtering out the electronic message if information regarding the sender is listed on the list of blocked addresses. 
     
     
       48. The medium of  claim 24  wherein the program instructions additionally comprise a step of automatically adding information regarding the sender to the list of accepted senders. 
     
     
       49. The medium of  claim 24  wherein the program instructions additionally comprise a step of determining if the received electronic message is properly addressed to a recipient. 
     
     
       50. The medium of  claim 49  wherein the received electronic message is filtered out if the received electronic message is not properly addressed to the recipient. 
     
     
       51. The medium of  claim 24  wherein the program instructions additionally comprise:
   a step of comparing the sender's address to a list of blocked senders; and        wherein the step of sending a second challenge message back to the sender comprises sending a second challenge message back to the sender if the sender's address is valid, the sender's address is not contained in the list of accepted senders, the sender's address is not contained in the list of blocked senders and the electronic message does not include the first token.     
     
     
       52. The medium of  claim 24  wherein the program instructions additionally comprise:
   automatically accepting the electronic message without filtering out the electronic message, if the electronic message includes:      the first token that indicates that the electronic message is a reply to the first challenge message; and        a correct response to a prompt of the first challenge message.       
     
     
       53. The medium of  claim 24  wherein the program instructions additionally comprise:
   automatically adding the sender's address to the list of accepted senders, if the electronic message includes:      the first token that indicates that the electronic message is a reply to the first challenge message; and        a correct response to a prompt of the first challenge message.       
     
     
       54. The medium of  claim 24  wherein the program instructions additionally comprise:
   automatically adding the sender's address to a list of blocked senders, if the electronic message includes:      the first token that indicates that the electronic message is a reply to the first challenge message; and        an incorrect response to a prompt of the first challenge message.       
     
     
       55. The medium of  claim 24  wherein the program instructions additionally comprise:
   automatically deleting the electronic message, if the electronic message includes:      the first token that indicates that the electronic message is a reply to the first challenge message; and        an incorrect response to a prompt of the first challenge message.       
     
     
       56. The medium of  claim 24  wherein the program instructions additionally comprise:
   receiving a response to the prompt of the second challenge message; and        automatically accepting the electronic message without filtering out the electronic message, if the received response includes:      the second token; and        a correct response to the prompt of the second challenge message.       
     
     
       57. The medium of  claim 24  wherein the program instructions additionally comprise:
   receiving a response to the prompt of the second challenge message; and        automatically adding the sender's address to the list of accepted senders, if the received response includes:      the second token; and        a correct response to the prompt of the second challenge message.       
     
     
       58. The medium of  claim 24  wherein the program instructions additionally comprise:
   receiving a response to the prompt of the second challenge message; and        automatically adding the sender's address to a list of blocked senders, if the received response includes:      the second token; and        an incorrect response to the prompt of the second challenge message.       
     
     
       59. The medium of  claim 24  wherein the program instructions additionally comprise:
   receiving a response to the prompt of the second challenge message; and        automatically deleting the electronic message, if the received response includes:      the second token; and        an incorrect response to the prompt of the second challenge message.       
     
     
       60. The method of  claim 30  additionally comprising:
   receiving a response to the prompt and the legal notice of the second challenge message; and        automatically accepting the electronic message without filtering out the electronic message, if the received response is correct.     
     
     
       61. The method of  claim 30  additionally comprising:
   receiving a response to the prompt and the legal notice of the second challenge message; and        automatically adding the sender's address to the list of accepted senders, if the received response is correct.     
     
     
       62. The method of  claim 30  additionally comprising:
   receiving a response to the prompt and the legal notice of the second challenge message; and        automatically adding the sender's address to a list of blocked senders, if the received response is incorrect.     
     
     
       63. The method of  claim 30  additionally comprising:
   receiving a response to the prompt and the legal notice of the second challenge message; and        automatically deleting the electronic message, if the received response is incorrect.     
     
     
       64. A non- transitory computer readable medium containing program instructions for filtering electronic messages, the program instructions comprising:      a )  receiving a first electronic message from a sender, the first electronic message including an address field containing a sender's address;        b )  comparing the sender's address to a list of accepted senders;        c )  comparing the sender's address to a list of blocked senders;        d )  applying a heuristic to the sender's address to determine if the sender's address is formatted according to a message standard of a messaging medium of transmission through which the first electronic message is received in order to make a determination of whether the sender's address is valid or invalid;        e )  analyzing the first electronic message to determine whether the first electronic message is properly addressed to one or more recipients in at least one recipient designation;        f )  analyzing the first electronic message to determine whether the first electronic message includes a first token that indicates that the first electronic message is a reply to a challenge message;        g )  sending a challenge message back to the sender via the sender's address if:      the sender's address is not contained in the list of accepted senders,        the sender's address is not contained in the list of blocked senders,        the sender's address is valid,        the first electronic message is properly addressed to one or more recipients in at least one recipient designation, and        the first electronic message does not include the first token,        wherein the challenge message includes a prompt designed to be answered by a person and not a machine and wherein the challenge message further includes a second token;          h )  receiving a second electronic message from the sender that includes the second token, the second electronic message including an answer to the prompt in the challenge message;        i )  analyzing the answer to the prompt to determine whether the answer to the prompt is correct;        k )  sending the second electronic message to a message folder accessible by a user to view the second electronic message; and        j )  automatically adding the sender's address to the list of accepted senders when the answer to the prompt in the challenge message is correct.     
     
     
       65. The medium of  claim 64  wherein the program instructions additionally comprise filtering out the first electronic message when:
   the sender's address is not contained in the list of blocked senders,        the sender's address is invalid, or        the first electronic message is not properly addressed to one or more recipients in at least one recipient designation.