RFC 2505 (rfc2505) - Page 1 of 24

Anti-Spam Recommendations for SMTP MTAs

Network Working Group                                        G. Lindberg
Request for Comments: 2505             Chalmers University of Technology
BCP: 30                                                    February 1999
Category: Best Current Practice


                Anti-Spam Recommendations for SMTP MTAs

Status of this Memo

   This document specifies an Internet Best Current Practices for the
   Internet Community, and requests discussion and suggestions for
   improvements.  Distribution of this memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (1999).  All Rights Reserved.

Abstract

   This memo gives a number of implementation recommendations for SMTP,
   [1], MTAs (Mail Transfer Agents, e.g. sendmail, [8]) to make them
   more capable of reducing the impact of spam(*).

   The intent is that these recommendations will help clean up the spam
   situation, if applied on enough SMTP MTAs on the Internet, and that
   they should be used as guidelines for the various MTA vendors. We are
   fully aware that this is not the final solution, but if these
   recommendations were included, and used, on all Internet SMTP MTAs,
   things would improve considerably and give time to design a more long
   term solution. The Future Work section suggests some ideas that may
   be part of such a long term solution. It might, though, very well be
   the case that the ultimate solution is social, political, or legal,
   rather than technical in nature.

   The implementor should be aware of the increased risk of denial of
   service attacks that several of the proposed methods might lead to.
   For example, increased number of queries to DNS servers and increased
   size of logfiles might both lead to overloaded systems and system
   crashes during an attack.

   A brief summary of this memo is:

   o   Stop unauthorized mail relaying.
   o   Spammers then have to operate in the open; deal with them.
   o   Design a mail system that can handle spam.





Lindberg                 Best Current Practice