SPF DoS Exploitation
This document describes an email induced Denial of Service threat from SPF script used to evaluate the association of a source domain- name with the sending-system. The SPF script attempts to establish the domain-name association through the construction of an extensive IP address list of all sending-systems. Expectations of an association have become problematic, as message handling might be negatively affected without an apparent domain-name relationship discovered between the sending-system and either the message envelope or the message itself.