Abstract: A recipient computer system may receive one or more electronic messages. The recipient computer system may send one, two, or more challenge messages to the sender of the electronic messages in determining whether to deliver the electronic message. The recipient computer system may accept or reject an electronic message based on the response, or lack of response, to the challenge messages. The recipient computer system may send two or more challenge messages at intervals. A sender computer system may record activity of the sender computer system for a recipient computer system to use in determining whether to deliver an electronic message. A sender computer system may provide a summary of that activity with an electronic message. A sender computer system may provide an authorization key for a recipient computer system to use in determining whether to deliver an electronic message. The authorization key may be generated by a third party.

Abstract: A recipient computer system may receive one or more electronic messages. The recipient computer system may send one, two, or more challenge messages to the sender of the electronic messages in determining whether to deliver the electronic message. The recipient computer system may accept or reject an electronic message based on the response, or lack of response, to the challenge messages. The recipient computer system may send two or more challenge messages at intervals. A sender computer system may record activity of the sender computer system for a recipient computer system to use in determining whether to deliver an electronic message. A sender computer system may provide a summary of that activity with an electronic message. A sender computer system may provide an authorization key for a recipient computer system to use in determining whether to deliver an electronic message. The authorization key may be generated by a third party.

Abstract: A recipient computer system may receive one or more electronic messages. The recipient computer system may send one, two, or more challenge messages to the sender of the electronic messages in determining whether to deliver the electronic message. The recipient computer system may accept or reject an electronic message based on the response, or lack of response, to the challenge messages. The recipient computer system may send two or more challenge messages at intervals. A sender computer system may record activity of the sender computer system for a recipient computer system to use in determining whether to deliver an electronic message. A sender computer system may provide a summary of that activity with an electronic message. A sender computer system may provide an authorization key for a recipient computer system to use in determining whether to deliver an electronic message. The authorization key may be generated by a third party.

Abstract: A recipient computer system may receive one or more electronic messages. The recipient computer system may send one, two, or more challenge messages to the sender of the electronic messages in determining whether to deliver the electronic message. The recipient computer system may accept or reject an electronic message based on the response, or lack of response, to the challenge messages. The recipient computer system may send two or more challenge messages at intervals. A sender computer system may record activity of the sender computer system for a recipient computer system to use in determining whether to deliver an electronic message. A sender computer system may provide a summary of that activity with an electronic message. A sender computer system may provide an authorization key for a recipient computer system to use in determining whether to deliver an electronic message. The authorization key may be generated by a third party.

Abstract: A system may include an electronic messaging system that may access user identifier information, which may be used to identify self-addressed electronic messages. The electronic messaging system may determine how to process an incoming electronic message using at least a portion of the user identifier information. The electronic messaging system determines whether to send a challenge-response message to a sender of an electronic message using at least a portion of the user identifier information. The electronic messaging system may be configured to identify self-addressed electronic messages and, in response to such identification, process the messages appropriately.

Abstract: Systems and methods for delivering solicited electronic messages to a client. Senders of electronic messages become authorized senders and electronic messages from the authorized senders are delivered to the intended recipients. Electronic messages from unauthorized senders are not delivered. A sender becomes authorized when a user includes a tracker in the user address that is associated with a particular sender. Electronic messages that include the tracker are only delivered if the sender is the same sender that is associated with the tracker provided by the user. Senders are also authorized by detecting when the user provides a user address to a sender. Users are given the opportunity to opt-in to receiving electronic messages from senders that have registered with the electronic messaging service that provides electronic message services to the users. Authorizing senders in this manner permits the delivery of solicited messages while rejecting unsolicited messages.

Abstract: A recipient computer system may receive one or more electronic messages. The recipient computer system may send one, two, or more challenge messages to the sender of the electronic messages in determining whether to deliver the electronic message. The recipient computer system may accept or reject an electronic message based on the response, or lack of response, to the challenge messages. The recipient computer system may send two or more challenge messages at intervals. A sender computer system may record activity of the sender computer system for a recipient computer system to use in determining whether to deliver an electronic message. A sender computer system may provide a summary of that activity with an electronic message. A sender computer system may provide an authorization key for a recipient computer system to use in determining whether to deliver an electronic message. The authorization key may be generated by a third party.

Abstract: A method is provided for preventing the transmission of unsolicited phone calls. The telephone number corresponding to the source of the phone call is first compared with a reject list and with an approved list to determine whether the call should be transmitted to the user. If the telephone number corresponding to the source of the phone call is not on either list, a registration procedure is carried out. Upon being successfully registered, the phone call is transmitted to the user and the source is added to the approved list.