SMTP Sentinel Gateway Server

Enterprise Edition  >  SMTP Gateway Server  >  Technical Overview

Technical Overview

The Death2Spam SMTP Gateway is designed to work alongside your firewall, to guard against malicious or unsolicited inbound email. It reviews every incoming message and its attachments, and redirects or eliminates undesirable content.

D2S is an SMTP proxy application, and normally stands in front of your email system. It is compatible with any SMTP-based email system, and can be deployed on any operating system which supports an up-to-date Java Runtime Environment. For a full list of prerequisites, please see the relevant System Requirements page.

Death2Spam is a modern Mail Application Server which fully supports multi-threading and multiple CPUs. It should normally be installed behind your firewall or inside the DMZ.

Message Processing Cycle

A brief description of the Death2Spam processing cycle follows:

• Death2Spam listens for incoming SMTP email.
• Upon receiving an inbound message, Death2Spam deconstructs the message headers, the body, and each attachment, then evaluates the content of the entire message (including the attachments) word by word.
• Each word is compared against the probability of it being a spam word, or conversely a good word (or, in the case of Death2Spam Anti-Virus, a viral signature token).
• A total probability score for the message is calculated based on the occurrence of spam and good words.
• The score is compared to configurable limits for good, spam and unsure messages (and virus if installed), and the message is flagged accordingly. All messages are kept for a limited period of time so the user can re-train the spam database.
• If the message is good or unsure, it is forwarded on to the final SMTP destination.

There are a wide range of configuration options which affect the behaviour of a Death2Spam server, some of which alter the basic operation as described above.