The techniques described in this document predicate system access to the inbound Mail Exchanger(s) for the internet domain where you receive e-mail. Essentially, you need to be able to install software and/or modify the configuration files for the Mail Transport Agent on that system.

Although the discussions in this document are conceptual in nature and can be incorporated into a number of different MTAs, a sample Exim 4 implementation is provided. This implementation, in turn, incorporates other software tools, such as SpamAssassin. See Appendix A, Exim Implementation for details.