Patent ID: 8230020

Claim:
A method for filtering an incoming electronic message sent by a sender and addressed to an intended user, the method comprising: providing, by the intended user, a predetermined identifier to the sender, the predetermined identifier being associated with the sender; providing, by a system, a temporary identifier, wherein the temporary identifier is included in an outgoing electronic message sent by the intended user to the sender, said temporary identifier identifying at least one of a moment at which the outgoing electronic message was sent, a destination to which the outgoing electronic message was sent, and a content of the outgoing electronic message, wherein said temporary identifier is appended to an alias related to a name of the intended user and included in a source header of the outgoing electronic message in a way that does not modify an actual electronic address of the intended user included in the same source header; receiving, by the system, the incoming electronic message from the sender; processing, by the system, the incoming electronic message to determine whether the incoming electronic message is a response message sent in response to a challenge message, and upon determining that the incoming electronic message is not a response message sent in response to a challenge message, detect a presence of the temporary identifier or the predetermined identifier in the alias related to the name of the intended user in a destination header of the incoming electronic message, wherein the presence of at least one of the temporary identifier and the predetermined identifier in the alias does not modify an actual electronic address of the intended user included in the same destination header; upon detection of either one or both of the temporary identifier and the predetermined identifier, allowing a delivery of the incoming electronic message to the intended user, and upon detection of an absence of the temporary identifier and the predetermined identifier in the incoming electronic message: storing the incoming electronic message, and sending a challenge message including a temporary challenge identifier associated with the stored incoming electronic message to the sender, the challenge message including a challenge designed to be answered by a person and not a machine, wherein determining whether the incoming electronic message is a response message sent in response to a challenge message includes determining whether the incoming electronic message includes a temporary challenge identifier included with a previously sent challenge message.