The simplicity of SMTP mail can be combined with the robustness of the sendmail MTA program and misused in numerous ways to create extraordinary and powerful e-mail bombs. These e-mail bombs can be launched in many different attack scenarios which can easily flood and shut down chains of SMTP mail servers. Sendmail-based SMTP mail relays also can be used covertly to distribute messages and files that could be very damaging to the integrity and brands of victims. This paper discusses mail-bombing techniques, automated attack tools, and countermeasures. Also discussed is an actual Internet based attack that was launched in 1997 on the Langley AFB SMTP e-mail infrastructure. We also present an analysis of the cyber-attack, graphs illustrating the attack-volume, and a statistical e-mail bomb early-warning system.