Patent ID: 8180835

Claim:
A system for controlling electronic mail flood attacks comprising: a network interface; a suspicious address class in a set of suspicious address classes; a counter associated with the suspicious address class, wherein the counter counts active connections originating from the suspicious address class to the network interface; an SMTP handler configured to process electronic mail messages, wherein whenever the SMTP handler receives an email request from the suspicious address class and at least one of a set of at least one failure criteria is met, the SMTP hander issues a temporary failure message, wherein the set of at least one failure criteria comprises a first criterion which is met when the counter has reached a predetermined limit; a first timer, wherein the first timer is restarted whenever the counter falls below the predetermined limit and expires after a first predetermined interval, wherein the set of at least one failure criteria further comprises a second criterion which is met when the first timer has been restarted and has not expired; and a second timer, wherein whenever any one of the set of at least one failure criteria has been met by a previous email request originating from the suspicious address class, the second timer is restarted and expires after a second predetermined interval, wherein the set of at least one failure criteria further comprises a third criterion which is met when the second timer has been restarted and has not expired.