By telneting directly to a mail server and manually speaking SMTP, one can easily send mail from any address specified - meaning that mail can be sent from fake addresses while the sender's real address is untraceable.
destructive program [F-Prot]Flooder.MailSpam.MailBomb.02 [Kaspersky]MailBomb [McAfee]Mailbomb!Trojan [Computer Associates]Trj/Mailbomb [Panda]
bomb.exe