Method and apparatus for filtering electronic messages
First Claim
1. A method for processing an email message having message content and sent by a remote server in accordance with a communications protocol, the method comprising:
- (a) establishing a communications connection with the remote server;
(b) exchanging a plurality of session messages defining a communications session with the remote server, at least some of which are separate from the message content;
(c) accepting from the remote server session data pertaining to the communications connection, including information pertaining to at least one of the following;
the remote server, the sender of the email message, the destination of the email message;
(d) determining if the session data meets criteria associated with legitimate messages;
(e) if the session data does not meet the criteria associated with the legitimate messages, testing the behavior of the remote server by sending to the remote server at least one stimulus signal configured to generate a machine-originated response from the remote server in accordance with the communications protocol to determine if the remote server is operation in accordance with the communications protocol, the testing initiated during the communications session; and
(f) processing the communications connection in response to whether the remote server is operating in accordance with the communications protocol;
wherein the at least one stimulus signal is one of a command and a reply, the format and content of which are specified by the communications protocol.
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Accused Products
Abstract
A method is provided for filtering electronic messages such as unsolicited bulk email. The method includes establishing a communications connection with the remote server under the Simple Email Transfer Protocol or other suitable protocol; accepting session data from the remote server; and determining if the session data meets criteria associated with legitimate messages. If the data pertaining to the connection does not meet the criteria associated with legitimate messages, then one or more stimulus signals are sent to the remote server. If the server responds to the stimulus signal in the manner required by the communications protocol, then the session can be added to a database of known sessions. The session is then terminated by responding to the server with a temporary error message in accordance with the protocol. If the remote server is a legitimate server complying with the STMP, it will resend the message after a prescribed time period.
23 Citations
21 Claims
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1. A method for processing an email message having message content and sent by a remote server in accordance with a communications protocol, the method comprising:
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(a) establishing a communications connection with the remote server; (b) exchanging a plurality of session messages defining a communications session with the remote server, at least some of which are separate from the message content; (c) accepting from the remote server session data pertaining to the communications connection, including information pertaining to at least one of the following;
the remote server, the sender of the email message, the destination of the email message;(d) determining if the session data meets criteria associated with legitimate messages; (e) if the session data does not meet the criteria associated with the legitimate messages, testing the behavior of the remote server by sending to the remote server at least one stimulus signal configured to generate a machine-originated response from the remote server in accordance with the communications protocol to determine if the remote server is operation in accordance with the communications protocol, the testing initiated during the communications session; and (f) processing the communications connection in response to whether the remote server is operating in accordance with the communications protocol; wherein the at least one stimulus signal is one of a command and a reply, the format and content of which are specified by the communications protocol. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A method for processing a message sent by a remote server in accordance with a communications protocol, wherein the message includes an envelope and a message content, comprising:
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(a) establishing a communications connection with the remote server; (b) accepting from the remote server session data pertaining to the connection, including information pertaining to at least one of the following;
the remote server;
the sender of the message;
the destination of the message;(c) determining if the session data meets criteria associated with legitimate messages; (d) sending one or more stimulus signals to the remote server if the session does not meet the criteria associated with legitimate messages; and (e) processing the connection in response to whether the remote server responds to the stimulus signal in the manner required by the communications protocol; wherein determining if the session data meets criteria associated with legitimate messages further comprises; determining if the connection is a priority connection; accepting the message content if it is a priority connection; providing a database of known connections; if the connection is not a priority connection, then determining if the connection is a known connection by reference to the database of known connections; if the connection is a known connection, then determining if the, connection meets criteria associated with legitimate messages; if the connection is a known connection and if the connection meets criteria associated with legitimate messages, then accepting the connection; if the connection is a known connection but does not meet the criteria associated with legitimate messages, then updating the database of information about known connections and sending an error code to the remote server which error code is prescribed under the protocol as requiring the remote server to resend the message after a period of time. - View Dependent Claims (19)
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20. An apparatus for processing an email message having an envelope and a message content and sent by a remote server in accordance with the SMTP communications protocol, comprising:
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a communications port adapted for establishing a communications connection with the remote server; a database of known connections; a processor coupled to the communications port and the database of known connections and adapted to; exchange a plurality of session messages defining a communications session with the remote server, at least some of which are separate from the message content; accept as input from the remote server session data pertaining to the communications connection, including information pertaining to at least one of the following;
the remote server, the sender of the email message, the destination of the email message;use the database of known connections to determine if the session data pertaining to the communications connection meets criteria associated with legitimate messages; if the session data does not meet the criteria associated with the legitimate messages, test the behavior of the remote server by sending to the remote server at least one stimulus signal configured to generate a response from the remote server in accordance with the SMTP communications protocol, wherein the at least one of stimulus signal is one of a command and a reply, the format and content of which are specified by the SMTP communications protocol, the testing initiated during the communications session; and process the communications connection in response to whether the remote server responds to the stimulus signal in the manner required by the SMTP communications protocol.
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21. A computer program product for processing an email message having message content and sent by a remote server in accordance with a communications protocol, comprising:
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a computer data storage medium; computer program instructions, recorded on the computer data storage medium, executable by a computer processor to; establish a communications connection with the remote server; exchange a plurality of session messages defining a communications session, at least some of which are separate from the message content; accept as input from the remote server session data pertaining to the communications connection, including information pertaining to at least one of the following;
the remote server, the sender of the email message, the destination of the email message;use a database of known connections to determine if the session data pertaining to the communications connection meets criteria associated with legitimate messages; if the session data does not meet the criteria associated with the legitimate messages, test the behavior of the remote server to determine if it complies with the communications protocol by sending to the remote server a stimulus signal configured to stimulate a response from the remote server in accordance with the communications protocol, the testing initiated during the communications session; and process the communications connection in response to whether the remote server responds to the stimulus signal in the manner required by the communications protocol; wherein the stimulus signal is one of a command and a reply, the format and content of which are specified by the communications protocol.
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Specification