469 lines
6.4 KiB
HTML
469 lines
6.4 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
|
|
<HTML
|
|
><HEAD
|
|
><TITLE
|
|
>Spam Filtering for Mail Exchangers</TITLE
|
|
><META
|
|
NAME="GENERATOR"
|
|
CONTENT="Modular DocBook HTML Stylesheet Version 1.7"><LINK
|
|
REL="NEXT"
|
|
TITLE="Introduction"
|
|
HREF="introduction.html"><META
|
|
NAME="KEYWORD"
|
|
CONTENT="anti-spam"><META
|
|
NAME="KEYWORD"
|
|
CONTENT="anti-virus"><META
|
|
NAME="KEYWORD"
|
|
CONTENT="bogus virus warnings"><META
|
|
NAME="KEYWORD"
|
|
CONTENT="collateral spam"><META
|
|
NAME="KEYWORD"
|
|
CONTENT="delivery status notification"><META
|
|
NAME="KEYWORD"
|
|
CONTENT="dsn"><META
|
|
NAME="KEYWORD"
|
|
CONTENT="exim"><META
|
|
NAME="KEYWORD"
|
|
CONTENT="exim4"><META
|
|
NAME="KEYWORD"
|
|
CONTENT="exiscan"><META
|
|
NAME="KEYWORD"
|
|
CONTENT="exiscan-acl"><META
|
|
NAME="KEYWORD"
|
|
CONTENT="greylisting"><META
|
|
NAME="KEYWORD"
|
|
CONTENT="junk mail"><META
|
|
NAME="KEYWORD"
|
|
CONTENT="sa-exim"><META
|
|
NAME="KEYWORD"
|
|
CONTENT="smtp"><META
|
|
NAME="KEYWORD"
|
|
CONTENT="spam"><META
|
|
NAME="KEYWORD"
|
|
CONTENT="spamassassin"><META
|
|
NAME="KEYWORD"
|
|
CONTENT="teergrubing"><META
|
|
NAME="KEYWORD"
|
|
CONTENT="transaction delay"></HEAD
|
|
><BODY
|
|
CLASS="book"
|
|
BGCOLOR="#FFFFFF"
|
|
TEXT="#000000"
|
|
LINK="#0000FF"
|
|
VLINK="#840084"
|
|
ALINK="#0000FF"
|
|
><DIV
|
|
CLASS="BOOK"
|
|
><A
|
|
NAME="AEN1"
|
|
></A
|
|
><DIV
|
|
CLASS="TITLEPAGE"
|
|
><H1
|
|
CLASS="title"
|
|
><A
|
|
NAME="AEN2"
|
|
></A
|
|
>Spam Filtering for Mail Exchangers</H1
|
|
><H2
|
|
CLASS="subtitle"
|
|
>How to reject junk mail in incoming SMTP transactions.</H2
|
|
><H3
|
|
CLASS="author"
|
|
><A
|
|
NAME="AEN6"
|
|
></A
|
|
>Tor Slettnes</H3
|
|
><DIV
|
|
CLASS="affiliation"
|
|
><DIV
|
|
CLASS="address"
|
|
><P
|
|
CLASS="address"
|
|
><TT
|
|
CLASS="email"
|
|
><<A
|
|
HREF="mailto:tor@slett.net"
|
|
>tor@slett.net</A
|
|
>></TT
|
|
></P
|
|
></DIV
|
|
></DIV
|
|
><H4
|
|
CLASS="EDITEDBY"
|
|
>Edited by</H4
|
|
><H3
|
|
CLASS="editor"
|
|
>Joost De Cock</H3
|
|
><H3
|
|
CLASS="editor"
|
|
>Devdas Bhagat</H3
|
|
><H3
|
|
CLASS="editor"
|
|
>Tom Wright</H3
|
|
><P
|
|
CLASS="edition"
|
|
>Version 1.0 -- Release Edition </P
|
|
><HR></DIV
|
|
><DIV
|
|
CLASS="TOC"
|
|
><DL
|
|
><DT
|
|
><B
|
|
>Table of Contents</B
|
|
></DT
|
|
><DT
|
|
><A
|
|
HREF="introduction.html"
|
|
>Introduction</A
|
|
></DT
|
|
><DD
|
|
><DL
|
|
><DT
|
|
>1. <A
|
|
HREF="intro-purpose.html"
|
|
>Purpose of this Document</A
|
|
></DT
|
|
><DT
|
|
>2. <A
|
|
HREF="intro-audience.html"
|
|
>Audience</A
|
|
></DT
|
|
><DT
|
|
>3. <A
|
|
HREF="intro-updates.html"
|
|
>New versions of this document</A
|
|
></DT
|
|
><DT
|
|
>4. <A
|
|
HREF="intro-history.html"
|
|
>Revision History</A
|
|
></DT
|
|
><DT
|
|
>5. <A
|
|
HREF="intro-credits.html"
|
|
>Credits</A
|
|
></DT
|
|
><DT
|
|
>6. <A
|
|
HREF="intro-feedback.html"
|
|
>Feedback</A
|
|
></DT
|
|
><DT
|
|
>7. <A
|
|
HREF="intro-translations.html"
|
|
>Translations</A
|
|
></DT
|
|
><DT
|
|
>8. <A
|
|
HREF="intro-copyright.html"
|
|
>Copyright information</A
|
|
></DT
|
|
><DT
|
|
>9. <A
|
|
HREF="intro-prerequisites.html"
|
|
>What do you need?</A
|
|
></DT
|
|
><DT
|
|
>10. <A
|
|
HREF="intro-conventions.html"
|
|
>Conventions used in this document</A
|
|
></DT
|
|
><DT
|
|
>11. <A
|
|
HREF="intro-organization.html"
|
|
>Organization of this document</A
|
|
></DT
|
|
></DL
|
|
></DD
|
|
><DT
|
|
>1. <A
|
|
HREF="background.html"
|
|
>Background</A
|
|
></DT
|
|
><DD
|
|
><DL
|
|
><DT
|
|
>1.1. <A
|
|
HREF="whysmtptime.html"
|
|
>Why Filter Mail During the SMTP Transaction?</A
|
|
></DT
|
|
><DT
|
|
>1.2. <A
|
|
HREF="goodbadugly.html"
|
|
>The Good, The Bad, The Ugly</A
|
|
></DT
|
|
><DT
|
|
>1.3. <A
|
|
HREF="smtpintro.html"
|
|
>The SMTP Transaction</A
|
|
></DT
|
|
></DL
|
|
></DD
|
|
><DT
|
|
>2. <A
|
|
HREF="techniques.html"
|
|
>Techniques</A
|
|
></DT
|
|
><DD
|
|
><DL
|
|
><DT
|
|
>2.1. <A
|
|
HREF="smtpdelays.html"
|
|
>SMTP Transaction Delays</A
|
|
></DT
|
|
><DT
|
|
>2.2. <A
|
|
HREF="dnschecks.html"
|
|
>DNS Checks</A
|
|
></DT
|
|
><DT
|
|
>2.3. <A
|
|
HREF="smtpchecks.html"
|
|
>SMTP checks</A
|
|
></DT
|
|
><DT
|
|
>2.4. <A
|
|
HREF="greylisting.html"
|
|
>Greylisting</A
|
|
></DT
|
|
><DT
|
|
>2.5. <A
|
|
HREF="senderauth.html"
|
|
>Sender Authorization Schemes</A
|
|
></DT
|
|
><DT
|
|
>2.6. <A
|
|
HREF="datachecks.html"
|
|
>Message data checks</A
|
|
></DT
|
|
><DT
|
|
>2.7. <A
|
|
HREF="collateral.html"
|
|
>Blocking Collateral Spam</A
|
|
></DT
|
|
></DL
|
|
></DD
|
|
><DT
|
|
>3. <A
|
|
HREF="considerations.html"
|
|
>Considerations</A
|
|
></DT
|
|
><DD
|
|
><DL
|
|
><DT
|
|
>3.1. <A
|
|
HREF="multimx.html"
|
|
>Multiple Incoming Mail Exchangers</A
|
|
></DT
|
|
><DT
|
|
>3.2. <A
|
|
HREF="otherservers.html"
|
|
>Blocking Access to Other SMTP Servers</A
|
|
></DT
|
|
><DT
|
|
>3.3. <A
|
|
HREF="forwardedmail.html"
|
|
>Forwarded Mail</A
|
|
></DT
|
|
><DT
|
|
>3.4. <A
|
|
HREF="usersettings.html"
|
|
>User Settings and Data</A
|
|
></DT
|
|
></DL
|
|
></DD
|
|
><DT
|
|
>4. <A
|
|
HREF="qanda.html"
|
|
>Questions & Answers</A
|
|
></DT
|
|
><DT
|
|
>A. <A
|
|
HREF="exim.html"
|
|
>Exim Implementation</A
|
|
></DT
|
|
><DD
|
|
><DL
|
|
><DT
|
|
>A.1. <A
|
|
HREF="exim-prereq.html"
|
|
>Prerequisites</A
|
|
></DT
|
|
><DT
|
|
>A.2. <A
|
|
HREF="exim-configfile.html"
|
|
>The Exim Configuration File</A
|
|
></DT
|
|
><DT
|
|
>A.3. <A
|
|
HREF="exim-options.html"
|
|
>Options and Settings</A
|
|
></DT
|
|
><DT
|
|
>A.4. <A
|
|
HREF="exim-firstpass.html"
|
|
>Building the ACLs - First Pass</A
|
|
></DT
|
|
><DT
|
|
>A.5. <A
|
|
HREF="exim-smtpdelays.html"
|
|
>Adding SMTP transaction delays</A
|
|
></DT
|
|
><DT
|
|
>A.6. <A
|
|
HREF="exim-greylisting.html"
|
|
>Adding Greylisting Support</A
|
|
></DT
|
|
><DT
|
|
>A.7. <A
|
|
HREF="exim-spf.html"
|
|
>Adding SPF Checks</A
|
|
></DT
|
|
><DT
|
|
>A.8. <A
|
|
HREF="exim-mime.html"
|
|
>Adding MIME and Filetype Checks</A
|
|
></DT
|
|
><DT
|
|
>A.9. <A
|
|
HREF="exim-av.html"
|
|
>Adding Anti-Virus Software</A
|
|
></DT
|
|
><DT
|
|
>A.10. <A
|
|
HREF="exim-sa.html"
|
|
>Adding SpamAssassin</A
|
|
></DT
|
|
><DT
|
|
>A.11. <A
|
|
HREF="exim-sign.html"
|
|
>Adding Envelope Sender Signatures</A
|
|
></DT
|
|
><DT
|
|
>A.12. <A
|
|
HREF="exim-bounces.html"
|
|
>Accept Bounces Only for Real Users</A
|
|
></DT
|
|
><DT
|
|
>A.13. <A
|
|
HREF="exim-forward.html"
|
|
>Exempting Forwarded Mail</A
|
|
></DT
|
|
><DT
|
|
>A.14. <A
|
|
HREF="exim-final.html"
|
|
>Final ACLs</A
|
|
></DT
|
|
></DL
|
|
></DD
|
|
><DT
|
|
><A
|
|
HREF="gloss.html"
|
|
>Glossary</A
|
|
></DT
|
|
><DT
|
|
>B. <A
|
|
HREF="gpl.html"
|
|
>GNU General Public License</A
|
|
></DT
|
|
><DD
|
|
><DL
|
|
><DT
|
|
>B.1. <A
|
|
HREF="gpl-1.html"
|
|
>Preamble</A
|
|
></DT
|
|
><DT
|
|
>B.2. <A
|
|
HREF="gpl-2.html"
|
|
>TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION</A
|
|
></DT
|
|
><DT
|
|
>B.3. <A
|
|
HREF="gpl-3.html"
|
|
>How to Apply These Terms to Your New Programs</A
|
|
></DT
|
|
></DL
|
|
></DD
|
|
></DL
|
|
></DIV
|
|
><DIV
|
|
CLASS="LOT"
|
|
><DL
|
|
CLASS="LOT"
|
|
><DT
|
|
><B
|
|
>List of Tables</B
|
|
></DT
|
|
><DT
|
|
>1. <A
|
|
HREF="intro-conventions.html#conventiontable"
|
|
>Typographic and usage conventions</A
|
|
></DT
|
|
><DT
|
|
>1-1. <A
|
|
HREF="smtpintro.html#smtpdialogue"
|
|
>Simple SMTP dialogue</A
|
|
></DT
|
|
><DT
|
|
>A-1. <A
|
|
HREF="exim-smtpdelays.html#aclvarusage"
|
|
>Use of ACL connection/message variables</A
|
|
></DT
|
|
></DL
|
|
></DIV
|
|
></DIV
|
|
><DIV
|
|
CLASS="NAVFOOTER"
|
|
><HR
|
|
ALIGN="LEFT"
|
|
WIDTH="100%"><TABLE
|
|
SUMMARY="Footer navigation table"
|
|
WIDTH="100%"
|
|
BORDER="0"
|
|
CELLPADDING="0"
|
|
CELLSPACING="0"
|
|
><TR
|
|
><TD
|
|
WIDTH="33%"
|
|
ALIGN="left"
|
|
VALIGN="top"
|
|
> </TD
|
|
><TD
|
|
WIDTH="34%"
|
|
ALIGN="center"
|
|
VALIGN="top"
|
|
> </TD
|
|
><TD
|
|
WIDTH="33%"
|
|
ALIGN="right"
|
|
VALIGN="top"
|
|
><A
|
|
HREF="introduction.html"
|
|
ACCESSKEY="N"
|
|
>Next</A
|
|
></TD
|
|
></TR
|
|
><TR
|
|
><TD
|
|
WIDTH="33%"
|
|
ALIGN="left"
|
|
VALIGN="top"
|
|
> </TD
|
|
><TD
|
|
WIDTH="34%"
|
|
ALIGN="center"
|
|
VALIGN="top"
|
|
> </TD
|
|
><TD
|
|
WIDTH="33%"
|
|
ALIGN="right"
|
|
VALIGN="top"
|
|
>Introduction</TD
|
|
></TR
|
|
></TABLE
|
|
></DIV
|
|
></BODY
|
|
></HTML
|
|
> |