44 Eleventh Hour Security : Exam SY0-201 Study Guide to your organization during a cyber investigation, there are additional risks associated with sending SPAM via an open mail relay: DoS conditions: Although businesses often use large Internet pipes, a single mail relay can quickly clog this pipe, causing a DoS condition where legitimate business functions cease to operate owing to lack of net- work resources. Damage to brand : SPAM messages may include advertising, images, or in some cases viruses. If one of these viruses were to impact another organi- zation, especially a client, then they could see the incidents as an indica- tion to the company's internal security challenges and may affect future business. Blacklisted on SPAM sites: Blacklisting sites track computers on the Internet that have been reported to be a major source of originating SPAM. These blacklists are maintained by SPAM-fighting organizations and are used by several anti-SPAM products as the gospel to block e-mails origi- nating from computers on these SPAM lists. SECURING MAIL RELAYS