Active e-mail filter with challenge-response
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.
1. A method for filtering electronic mail (e-mail) at a central e-mail server comprising:
receiving an e-mail having a sender and a recipient;
categorizing, via the central e-mail server, a current level of security associated with the central e-mail server, wherein the current level of security corresponds to a type of filtering of e-mails to be performed by the central e-mail server on the received email;
generating instructions, via the central e-mail server, for a challenge message to be sent to the sender in response to the received e-mail, the challenge message is an active image-based challenge associated with the current level of security, in which a challenge question is part of a moving or changing image, wherein the challenge question is presented as scrolling text that is part of the moving or changing image and requires a correct e-mail response to be selected from a provided set comprising a plurality of possible e-mail responses;
waiting, for a pre-determined period of time via the central e-mail server, for a response message from the sender in response to the challenge message, wherein the response message addresses the challenge message sent by the central e-mail server;
receiving, via the central e-mail server, a response message from the sender;
evaluating, via the central e-mail server, the response message to classify the received e-mail and sender; and
transmitting, the received e-mail to the recipient via the central e-mail server, including information about the received e-mail and the sender facilitating user filtering of e-mails, wherein the recipient can store the filtered e-mail and provide a label for the sender based on the information about the filtered e-mail and the sender transmitted from the central e-mail server.
2. The method according to claim 1 , wherein the classification for the received email and the sender can be unwelcome and blocked.
3. The method according to claim 1 , wherein the classification for the received email and the sender can be welcome and approved.
4. The method according to claim 1 , wherein the challenge message sent to the sender of the received e-mail is obtained by the central e-mail server from a third party/external provider.
5. The method according to claim 1 , wherein the challenge message sent to the sender of the received e-mail is generated by the central e-mail server.
6. The method of claim 1 , wherein the challenge message sent to the sender of the received e-mail is based on user input selecting a particular challenge message to be sent to the sender.
7. A non-transitory computer-readable storage medium associated with a central server having embodied thereon a program, the program being executable by a processor to perform a method for filtering electronic mail (e-mail), the method comprising:
receiving, at a central e-mail server, an e-mail having a sender and a recipient;
categorizing, via the central e-mail server, a current level of security associated with the central e-mail server, wherein the current level of security corresponds to a type of filtering of e-mails to be performed by the central e-mail server on the received email;
generating instructions, via the central e-mail server, for a challenge message to be sent to the sender in response to the received e-mail, the challenge message is an active image-based challenge associated with the current level of security, in which a challenge question is part of a moving or changing image, wherein the challenge question is presented as scrolling text that is part of the moving or changing image and requires a correct e-mail response to be selected from a provided set comprising a plurality of possible e-mail responses,
waiting, for a pre-determined period of time via the central e-mail server, for a response message from the sender in response to the challenge message, wherein the response message addresses the challenge message sent by the central e-mail server;
receiving, via the central e-mail server, a response message from the sender;
evaluating, via the central e-mail server, the response message to classify the received e-mail and sender; and
transmitting, the received e-mail to the recipient via the central e-mail server, including information about the received e-mail and the sender facilitating user filtering of e-mails, wherein the recipient can store the filtered e-mail and provide a label for the sender based on the information about the filtered e-mail and the sender transmitted from the central e-mail server.
8. The non-transitory computer-readable storage medium of claim 7 , wherein the classification for the received email and the sender can be unwelcome and blocked.
9. The non-transitory computer-readable storage medium of claim 7 , wherein the classification for the received email and the sender can be welcome and approved.
10. The non-transitory computer-readable storage medium of claim 7 , wherein the challenge message is obtained from a third party/external provider.
11. The non-transitory computer-readable storage medium of claim 8 , wherein the challenge message is generated by the central e-mail server.
12. The non-transitory computer-readable storage medium of claim 8 , wherein the challenge message sent to the sender of the received e-mail is based on user input selecting a particular challenge message to be sent to the sender.