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 message including an address field containing a sender's address;   comparing the sender's address to a list of accepted senders;   sending a prompt back to the sender if the sender's address is not contained in the list of accepted senders, wherein the prompt is designed to be answered by a person and not a machine.   
     
     
       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. 
     
     
       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 blocked addresses and filtering out the message if information regarding the sender is listed on the list. 
     
     
       6. The method of  claim 1 , further comprising a step of automatically adding information regarding the sender to a list. 
     
     
       7. The method of  claim 1 , further comprising a step of determining if the received electronic message is properly addressed to a predetermined receiver. 
     
     
       8. The method of  claim 7 , wherein a message is filtered out if the received electronic message is not properly addressed to the predetermined receiver. 
     
     
       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 to the sender comprises sending a prompt 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. 
     
     
       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 computer readable medium containing program instructions for filtering electronic messages, the program instructions comprising:
 receiving an electronic message from a sender the message including an address field containing a sender's address;   comparing the sender's address to a list of accepted senders;   sending a prompt back to the sender if the sender's address is not contained in the list of accepted senders, wherein the prompt is designed to be answered by a person and not a machine.   
     
     
       25. The medium of  claim 24  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. 
     
     
       26. The medium of  claim 24  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. 
     
     
       27. The medium of  claim 26  additionally comprising 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;   sending a challenge back to the sender 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.   
     
     
       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 , 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. 
     
     
       37. The method of  claim 36 , wherein the received message is filtered out if it is not properly addressed to a predetermined receiver. 
     
     
       38. A non-transitory computer readable storage medium containing program instructions for filtering electronic messages, the program instructions comprising:
 receiving a first electronic message from a sender, the first electronic message including an address field containing a sender's address;   comparing the sender's address to a list of accepted senders;   sending a challenge including a prompt back to the sender if the sender's address is not contained in the list of accepted senders, wherein the prompt is designed to be answered by a person and not a machine;   receiving, from the sender, a response to the challenge;   determining that the received response to the challenge is valid;   in response to determining the received response to the challenge is valid, adding the sender's address to the list of accepted senders;   receiving, via a user interface, manually-entered user input indicating that the sender's address should be added to a list of blocked senders; and   in response to receiving the manually-entered user input indicating that the sender's address should be added to a list of blocked senders:
 adding the sender's address to the list of blocked senders, wherein the addition of the sender's address to the list of blocked senders takes precedence over the prior addition of the sender's address to the list of accepted senders, such that incoming electronic messages from the sender's address will be filtered out. 
   
     
     
       39. The medium as in claim 38, wherein the addition of the sender's address to the list of blocked senders takes precedence over the prior addition of the sender's address to the list of accepted senders, such that incoming electronic messages from the sender's address will be filtered out by discarding the incoming electronic messages. 
     
     
       40. The medium as in claim 38, wherein the addition of the sender's address to the list of blocked senders takes precedence over the prior addition of the sender's address to the list of accepted senders, such that incoming electronic messages from the sender's address will be filtered out by placing the incoming electronic messages in a deleted items folder. 
     
     
       41. The medium as in claim 38, wherein the addition of the sender's address to the list of blocked senders takes precedence over the prior addition of the sender's address to the list of accepted senders, such that incoming electronic messages from the sender's address will be filtered out by placing the incoming electronic messages in a folder other than an inbox. 
     
     
       42. The medium as in claim 38, wherein the program instructions further comprise:
 receiving a second electronic message including an address field containing the sender's address;   determining that the sender's address contained in the address field of the second electronic message is contained in the list of blocked senders; and   in response to determining that the sender's address contained in the address field of the second electronic message is contained in the list of blocked senders, filtering out the second electronic message.   
     
     
       43. The medium as in claim 38, wherein the program instructions further comprise:
 receiving a second electronic message including an address field containing the sender's address;   determining that the sender's address contained in the address field of the second electronic message is contained in the list of blocked senders; and   in response to determining that the sender's address contained in the address field of the second electronic message is contained in the list of blocked senders, discarding the second electronic message.   
     
     
       44. The medium as in claim 38, wherein the program instructions further comprise:
 receiving a second electronic message including an address field containing the sender's address;   determining that the sender's address contained in the address field of the second electronic message is contained in the list of blocked senders; and   in response to determining that the sender's address contained in the address field of the second electronic message is contained in the list of blocked senders, placing the second electronic message in a deleted items folder.   
     
     
       45. The medium as in claim 38, wherein the program instructions further comprise:
 receiving a second electronic message including an address field containing the sender's address;   determining that the sender's address contained in the address field of the second electronic message is contained in the list of blocked senders; and   in response to determining that the sender's address contained in the address field of the second electronic message is contained in the list of blocked senders, placing the second electronic message in a folder other than an inbox.   
     
     
       46. A non-transitory computer readable storage 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;   determining whether the sender's address has a format that is valid for delivery; and   sending a challenge including a prompt back to the sender if the sender's address is not contained in the list of accepted senders and the sender's address has a format that is valid for delivery, wherein the prompt is designed to be answered by a person and not a machine.   
     
     
       47. The medium as in claim 46, wherein the act of determining whether the sender's address has a format that is valid for delivery includes:
 determining whether the sender's address includes an @ symbol.   
     
     
       48. The medium as in claim 46, wherein the act of determining whether the sender's address has a format that is valid for delivery includes:
 determining whether the sender's address includes a particular character.   
     
     
       49. The medium as in claim 46, wherein the act of determining whether the sender's address has a format that is valid for delivery includes:
 determining whether the sender's address lacks an @ symbol.   
     
     
       50. The medium as in claim 46, wherein the act of determining whether the sender's address has a format that is valid for delivery includes:
 determining whether the sender's address lacks a particular character.   
     
     
       51. The medium as in claim 46, wherein the program instructions further comprise:
 filtering out the electronic message if the sender's address does not have a format that is valid for delivery.   
     
     
       52. The medium as in claim 46, wherein the program instructions further comprise:
 discarding the electronic message if the sender's address does not have a format that is valid for delivery.   
     
     
       53. The medium as in claim 46, wherein the program instructions further comprise:
 placing the electronic message in a deleted items folder if the sender's address does not have a format that is valid for delivery.   
     
     
       54. The medium as in claim 46, wherein the program instructions further comprise:
 placing the electronic message in a folder other than an inbox if the sender's address does not have a format that is valid for delivery.   
     
     
       55. A non-transitory computer readable storage 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;   generating a reference identifier;   sending a challenge including a prompt back to the sender if the sender's address is not contained in the list of accepted senders, wherein the prompt is designed to be answered by a person and not a machine;
 wherein the challenge sent to the sender includes a body portion; 
 wherein the generated reference identifier is disposed within the body portion of the challenge sent to the sender; and 
 wherein the challenge sent to the sender is configured such that a response to the challenge includes the generated reference identifier; 
   receiving, from the sender, a response to the challenge, the received response to the challenge including the generated reference identifier; and   using the generated reference identifier of the received response to determine whether the received response is valid.   
     
     
       56. The medium as in claim 55, wherein the act of using the generated reference identifier of the received response to determine whether the received response is valid includes:
 using the reference identifier to identify the prompt of the challenge to which the received response is responding.   
     
     
       57. The medium as in claim 55, wherein the program instructions further comprise:
 in response to determining that the received response is valid, adding the sender's address to the list of accepted senders.   
     
     
       58. The medium as in claim 55, wherein the program instructions further comprise:
 in response to determining that the received response is not valid, adding the sender's address to a list of blocked senders.   
     
     
       59. A non-transitory computer readable storage 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;   generating a reference identifier;   sending a challenge including a prompt back to the sender if the sender's address is not contained in the list of accepted senders, wherein the prompt is designed to be answered by a person and not a machine;
 wherein the challenge sent to the sender further includes:
 a less-than symbol (“<”); 
 a greater-than symbol (“>”); and 
 the generated reference identifier disposed between the less-than symbol and the greater-than symbol; and 
 
 wherein the challenge sent to the sender is configured such that a response to the challenge includes the generated reference identifier; 
   receiving, from the sender, a response to the challenge, the received response to the challenge including the generated reference identifier; and   using the generated reference identifier of the received response to determine whether the received response is valid.   
     
     
       60. The medium as in claim 59, wherein the act of using the generated reference identifier of the received response to determine whether the received response is valid includes:
 using the reference identifier to identify the prompt of the challenge to which the received response is responding.   
     
     
       61. The medium as in claim 59, wherein the program instructions further comprise:
 in response to determining that the received response is valid, adding the sender's address to the list of accepted senders.   
     
     
       62. The medium as in claim 59, wherein the program instructions further comprise:
 in response to determining that the received response is not valid, adding the sender's address to a list of blocked senders.   
     
     
       63. The medium as in claim 62, wherein the program instructions further comprise:
 receiving a second electronic message including an address field containing the sender's address;   determining that the sender's address contained in the address field of the second electronic message is contained in the list of blocked senders; and   in response to determining that the sender's address contained in the address field of the second electronic message is contained in the list of blocked senders, filtering out the second electronic message.   
     
     
       64. A non-transitory computer readable storage medium containing program instructions for filtering electronic messages, the program instructions comprising:
 receiving a first electronic message from a sender, the first electronic message including an address field containing a sender's address;   comparing the sender's address to a list of accepted senders;   sending a challenge including a prompt back to the sender if the sender's address is not contained in the list of accepted senders, wherein the prompt is designed to be answered by a person and not a machine, wherein the challenge is configured to receive user input indicating an assent by the sender to be bound to a legal agreement;   receiving, from the sender, a response to the challenge;   determining, from the received response to the challenge, that the challenge received the user input indicating the sender's assent to be bound to the legal agreement;   determining the received response to the challenge is valid at least partially based on the determination that the challenge received the user input indicating the sender's assent to be bound to the legal agreement; and   in response to determining that the received response is valid, adding the sender's address to the list of accepted senders.