Active e-mail filter with challenge-response
First Claim
1. A method for filtering electronic mail (e-mail) sent to a user e-mail system comprising:
- receiving at the user e-mail system a current e-mail message sent from a sender address, wherein the e-mail system has a plurality of different levels of security ranging from high to low, each level of security associated with a different set of one or more e-mail filters;
determining that a current level of security has been selected by the user, wherein the current level of security as selected by the user is associated with a challenge-response filter;
determining that the current e-mail message is not a challenge e-mail response message sent from the sender address in response to a previous challenge rendered by the user e-mail system, the previous challenge having been identified at a computing device associated with the sender address by a valid challenge key in the previous challenge rendered by the user e-mail system, the valid challenge key identifying a message as a challenge requiring a challenge e-mail response message;
returning to the sender address a challenge that requires a correct challenge response, wherein the challenge rendered by the user'"'"'s e-mail system is selected from a plurality of challenges generated by an external provider of challenges, the challenge being sent to the sender address via e-mail;
storing the current e-mail message sent from the sender address in an intermediate buffer coupled to the user e-mail system;
receiving a challenge e-mail response message sent from the sender address in response to the challenge rendered by the user'"'"'s e-mail system; and
evaluating the challenge e-mail response message to determine whether the challenge response message includes a correct challenge response and corresponds to a formal criterion, wherein the formal criterion is a server of the sender being configured to accept e-mail, wherein future e-mail messages from senders associated with servers that do not accept e-mail are prevented from reaching an intended recipient at the user e-mail system.
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Accused Products
Abstract
When a user receives potential junk e-mail from an unknown sender address, an active filter installed in or cooperating with the user'"'"'s e-mail system sends a challenge e-mail back to the sender address. Unless the user receives a correct response e-mail from the sender address and/or a response that meets formal criteria, the active filter rejects the original e-mail and blocks future e-mail from that sender address. The challenge preferably includes a question that the sender must correctly answer in his response. The question is such that only humans can interpret and respond to it correctly. For example, the question may relate to and/or be incorporated in an image in the challenge. Lists of approved and blocked sender addresses are compiled. The user may directly enter addresses in the address lists. Addresses to which the user has sent e-mail may also be included directly in the approved list.
171 Citations
42 Claims
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1. A method for filtering electronic mail (e-mail) sent to a user e-mail system comprising:
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receiving at the user e-mail system a current e-mail message sent from a sender address, wherein the e-mail system has a plurality of different levels of security ranging from high to low, each level of security associated with a different set of one or more e-mail filters; determining that a current level of security has been selected by the user, wherein the current level of security as selected by the user is associated with a challenge-response filter; determining that the current e-mail message is not a challenge e-mail response message sent from the sender address in response to a previous challenge rendered by the user e-mail system, the previous challenge having been identified at a computing device associated with the sender address by a valid challenge key in the previous challenge rendered by the user e-mail system, the valid challenge key identifying a message as a challenge requiring a challenge e-mail response message; returning to the sender address a challenge that requires a correct challenge response, wherein the challenge rendered by the user'"'"'s e-mail system is selected from a plurality of challenges generated by an external provider of challenges, the challenge being sent to the sender address via e-mail; storing the current e-mail message sent from the sender address in an intermediate buffer coupled to the user e-mail system; receiving a challenge e-mail response message sent from the sender address in response to the challenge rendered by the user'"'"'s e-mail system; and evaluating the challenge e-mail response message to determine whether the challenge response message includes a correct challenge response and corresponds to a formal criterion, wherein the formal criterion is a server of the sender being configured to accept e-mail, wherein future e-mail messages from senders associated with servers that do not accept e-mail are prevented from reaching an intended recipient at the user e-mail system. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36)
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37. A system for filtering electronic mail (e-mail) sent to a user comprising:
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a network that receives and transmits e-mail; a computing device communicatively coupled to the network, the computing device associated with a recipient address and having a plurality of different levels of security ranging from high to low, each level of security associated with a different set of one or more e-mail filters, and wherein the computing device; receives a current e-mail message sent over the network from a sender address to the recipient address; determines that a current level of security has been selected by the user, wherein the current level of security as selected by the user is associated with a challenge-response filter, determines that the current e-mail message is not a challenge e-mail response message sent in response to a previous challenge initiated by the computing device, the previous challenge having been identified by a valid challenge key in the previous challenge rendered by the computing device, the valid challenge key identifying a message as a challenge requiring a challenge e-mail response message; sends to the sender address a challenge that requires a correct challenge response, wherein the challenge is selected from a plurality of challenges generated by an external provider of challenges, the external provider being communicatively coupled to the computing device and accessed over the network; stores the current e-mail message from the sender address in an intermediate storage buffer coupled to the computing device; receives a challenge e-mail response message from the sender address; and evaluates the challenge e-mail response message to determine whether the challenge e-mail response message includes a correct challenge response and corresponds to a formal criterion, wherein the formal criterion is a server of the sender address being configured to accept e-mail, wherein future e-mail messages from sender addresses associated with servers that do not accept e-mail are prevented from reaching an intended recipient at the computing device. - View Dependent Claims (38, 39, 40, 41)
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42. A non-transitory computer-readable storage medium having embodied thereon a program, the program being executable by a computer to perform a method for filtering electronic mail (e-mail) comprising:
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receiving a current e-mail message sent from a sender address in an e-mail system that has a plurality of different levels of security ranging from high to low, each level of security associated with a different set of one or more e-mail filters; determining that a current level of security has been selected by the user, wherein the current level of security as selected by the user is associated with a challenge-response filter; determining that the current e-mail message is not a challenge e-mail response message sent from the sender address in response to a previously rendered challenge, the previous challenge having been identified by a valid challenge key in the previously rendered challenge, the valid challenge key identifying a message as a challenge requiring a challenge e-mail response message; returning to the sender address a newly rendered challenge that requires a correct challenge response, wherein the newly rendered challenge is selected from a plurality of challenges generated by an external provider of challenges; storing the current e-mail message sent from the sender address to an intended recipient in an intermediate storage buffer; receiving a challenge e-mail response message sent from the sender address; and evaluating the challenge e-mail response message to determine whether the challenge e-mail response message includes both a correct challenge response and corresponds to a formal criterion, wherein the formal criterion is a server of the sender address being configured to accept e-mail, wherein future e-mail messages from senders associated with servers that do not accept e-mail are prevented from reaching an intended recipient.
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Specification