11. Organization of this document

This document is organized into the following chapters:

Background

General introduction to SMTP time filtering, and to SMTP.

Techniques

Various ways to block junk mail in an SMTP transaction.

Considerations

Issues that pertain to transaction time filtering.

Questions & Answers

My attempt at anticipating your questions, and then answering them.

A sample Exim implementation is provided in Appendix A, Exim Implementation.