MailVice Spam-Free Email

Stop the Bleeding

The first priority was to restore order to our failing email systems. The biggest threat was from the directory harvest attacks that delivered no real email, but simply used high speed probes to test for the existence of MILLIONS of combinations of email addresses in password cracking style. Several options already existed, but none of them really helped. If we reported that ALL email addresses existed (Microsoft's recommendation), it only served to invite a flood of non-deliverable spam later. Tar-pitting schemes (most popular in the UNIX world) didn't reduce the load, but instead created a snowball effect.  Many software packages were reviewed and all fell short of the task.

A super-light, super-high-volume message transfer agent (MTA) was created from scratch to handle the problem by load balancing final delivery to the real mail servers. The original job of the MTA was to stand on the front line and look for directory harvest attacks and thwart them by reporting that NO email addresses existed, an approach that was completely backwards from prior attempts. As the intruders became savvy to our method, which was also adopted by others, the actual number of attempts and the duration of the attacks started to decline. Along with the MTA's back-end load balancing, reliability had been restored.