System and method for detecting and defeating IP address spoofing in electronic mail messages

1. A method for detecting a spoofed network connection comprising:

receiving a connection from a client;

delaying sending a greeting message for a delay period, the delay period being less than or equal to a maximum tolerable delay, the maximum tolerable delay being the longest delay that would be tolerated by a valid client;

monitoring the connection during the delay period;

if a command is received from the client before the greeting is sent, then identifying the connection as the spoofed connection;

processing any electronic mail associated with the spoofed connection;

wherein a spoofed connection electronic-mail message is processed using a process selected from the group consisting of:

deleting the spoofed-connection electronic-mail message;

marking the spoofed-connection electronic-mail message; and

storing the spoofed-connection electronic-mail message in an electronic directory.

2. The method of claim 1 further comprising:

sending the greeting to the client upon completion of the delay period.

3. The method of claim 1 wherein the connection is a Transmission Control Protocol (TCP) connection.

4. The method of claim 1 wherein the client is a Mail Transfer Agent (MTA) or Mail User Agent (MUA).

5. The method of claim 1 wherein the received command is a Simple Mail Transfer Protocol (SMTP) command.

6. A method for detecting a spoofed network connection comprising:

receiving a first command at a server from a client;

delaying, for a delay period, a transmission of a reply associated with the first command, the delay period being less than or equal to a maximum tolerable delay, the maximum tolerable delay being the longest delay that would be tolerated by a valid client;

monitoring a connection between the server and the client during the delay period;

if a second command is received at the server before the reply is transmitted, then identifying the connection as the spoofed connection;

processing any electronic mail associated with the spoofed connection;

wherein a spoofed connection electronic-mail message is processed using a process selected from the group consisting of:

deleting the spoofed-connection electronic-mail message;

marking the spoofed-connection electronic-mail message; and

storing the spoofed-connection electronic-mail message in an electronic directory.

7. The method of claim 6 further comprising:

sending a greeting to the client when the connection is established with the server.

8. The method of claim 6 further comprising:

transmitting the reply upon completion of the delay period.

9. The method of claim 6 wherein the connection is a Transmission Control Protocol (TCP) connection.

10. The method of claim 6 wherein the client is a Mail Transfer Agent (MTA) or Mail User Agent (MUA).

11. The method of claim 6 wherein the received command is a Simple Mail Transfer Protocol (SMTP) command.

12. An apparatus for detecting a spoofed connection comprising:

means for detecting when a connection is established between the apparatus and a client device;

means for transmitting a greeting message or a reply or both to the client device;

means for delaying the transmitting means so that the greeting message or the reply or both are not transmitted during a delay period, the delay period being less than or equal to a maximum tolerable delay, the maximum tolerable delay being the longest delay that would be tolerated by a valid client; and

means for monitoring the connection to detect commands that are sent by the client device at least during the delay period;

if a command is received from the client before the greeting message or a reply or both is sent then identifying the connection as the spoofed connection;

means for processing any electronic mail associated with the spoofed connection;

wherein a spoofed connection electronic-mail message is processed using a process selected from the group consisting of:

deleting the spoofed-connection electronic-mail message;

marking the spoofed-connection electronic-mail message; and

storing the spoofed-connection electronic-mail message in an electronic directory.

13. The apparatus of claim 12 wherein the client device is a Mail Transfer Agent (MTA) or Mail User Agent (MUA).

14. The apparatus of claim 12 wherein the detecting means, the transmitting means, the delaying means, and the monitoring means comprise one or more processor-based devices running software algorithms to provide the detecting, transmitting, delaying and monitoring functions.

15. The apparatus of claim 12 wherein the connection is a Transmission Control Protocol (TCP) connection.

16. The apparatus of claim 12 wherein the commands are Simple Mail Transfer Protocol (SMTP) commands.