Processing a message based on a boundary IP address and decay variable

1. A non-transitory computer-readable storage medium having embodied thereon a program, the program being executable by a computer to perform a method of processing an electronic mail message based on a determined boundary IP address and decaying classification variable, the method comprising:

processing the header of an electronic-mail message to extract a plurality of candidate IP addresses and corresponding domains;

storing each extracted domain and IP address in an array;

locating a gateway IP address from the extracted candidate IP addresses stored in the array;

selecting the boundary IP address based on a pattern identified in a series of previously received electronic-mail messages;

looking up the boundary IP address and corresponding domain in a reputation table, wherein the corresponding domain is from a different hop along a path of the electronic-mail message than the boundary IP address and the presence of the boundary IP address and corresponding domain in the reputation table is included in a classification of the electronic mail-message, the reputation table including a decaying classification variable that reduces the effect of an older classification;

classifying the electronic-mail message and

processing the electronic-mail message in accordance with the classification of the electronic-mail message.

2. The non-transitory computer-readable storage medium of claim 1 , wherein the domain and IP address are extracted from each ‘received: from’ line in the electronic-mail message header.

3. The non-transitory computer-readable storage medium of claim 1 , wherein the gateway IP address is a known IP address within a trusted user network.

4. The non-transitory computer-readable storage medium of claim 1 , wherein the gateway IP address is located by marching down the array.

5. The non-transitory computer-readable storage medium of claim 4 , wherein a comparison is performed at each step of marching down the array.

6. The non-transitory computer-readable storage medium of claim 1 , wherein the boundary IP address is the IP address located after the gateway IP address.

7. The non-transitory computer-readable storage medium of claim 1 , wherein the boundary IP address is the IP address located last in the header of the electronic-mail message.

8. The non-transitory computer-readable storage medium of claim 1 , the method further comprising analyzing reverse domain information, wherein the results of the reverse domain analysis is also included in the classification of the electronic-mail message.

9. The non-transitory computer-readable storage medium of claim 8 , wherein analysis of the reverse domain information includes verifying that the domain is the same domain, the verification reflecting that the domain and associated IP address are trusted.

10. The non-transitory computer-readable storage medium of claim 1 , wherein the classification of the electronic-mail message is that the electronic-mail message involves spoofing of sender information.

11. The non-transitory computer-readable storage medium of claim 1 , wherein the classification of the electronic-mail message is that the message is spam.

12. The non-transitory computer-readable storage medium of claim 1 , wherein the classification of the electronic-mail message is that the message is not spam.

13. The non-transitory computer-readable storage medium of claim 1 , wherein the classification of the electronic-mail message is that the message is likely spam.

14. The non-transitory computer-readable storage medium of claim 1 , the method further comprising overriding a white list based on the classification of the electronic-mail message.

15. The non-transitory computer-readable storage medium of claim 1 , the method further comprising overriding a black list based on the classification of the electronic-mail message.

16. The non-transitory computer-readable storage medium of claim 1 , wherein decay of the classification variable is linear.

17. The non-transitory computer-readable storage medium of claim 1 , wherein decay of the classification variable is exponential.

18. The non-transitory computer-readable storage medium of claim 1 , wherein decay of the classification variable periodically occurs.

19. The non-transitory computer-readable storage medium of claim 1 , wherein decay of the classification variable occurs immediately prior to incrementing the variable.