WebSVN - Diff - Rev 6 and 46 - /trunk/debian/README.Debian

 ********************************
 * SHOULD YOU USE THIS PACKAGE? *
 ********************************
 Since version 4.50, Exim has the content-scanning extension formerly
 known as "exiscan" built-in. It has a number of advantages and
 disadvantages compared to SA-Exim.
 Advantages of built-in content-scanning interface:
  * One less configuration file to edit.
  * Spam control policy integrates better with Exim's ACL system.
  * It's possible to tell SA which user to scan for (the -u parameter of
    spamc). SA-Exim can't do that (yet).
  * Finer control over the mail header is possible, but not in a clean
    way (it involves putting all header fields you might possibly want
    to add in the report template, and using rather complicated
    expansion expressions to extract the wanted ones from
    $spam_report). At any rate, you can choose a prefix different from
    "X-Spam-".
 Advantages of SA-Exim:
  * It is possible to use the report_safe feature, which turns mail
    deemed to be spam into a message/rfc822 attachment of a report
    message. (Note however that if you do, then any X-SA-* fields added
    to help the greylisting module can't be removed.)
  * All the add_header and rewrite_header options in
    /etc/spamassassin/local.cf will be obeyed. In other words,
    everything will be *almost* as if you filtered the mail through
    spamassassin on the command line.
  * So-called teergrubing ("tarpitting") is possible in a way that
    isn't possible with exiscan (I'm not in any way saying that it
    works as a counterattack against spammers).
  * You can simply add the sa-exim package to a standard exim4
    installation and it should, in principle, instantly work (except
    you have to uncomment one line in sa-exim.conf).
 Both alternatives enable you to defer, greylist, reject, and blackhole
 mail, optionally saving copies, at configurable score levels.
 *****************
 * CONFIGURATION *
 *****************
 This version of the sa-exim package defaults to placing a configuration
 sniplet in /etc/exim4/conf.d/. Depending on what you have answered to the
 DebConf questions while configuring Exim4, the module will be loaded
 automatically, or human intervention is required.
 To find out what configuration file Exim4 is using, issue:
   $ exim4 -bV | tail -1
   Configuration file is /path/to/configfile
 If /path/to/configfile shows:
   - /etc/exim4/exim4.conf
     You are using the hand-crafted configuration file.
 	See the 'HAND-CRAFTED' section below.
   - /var/lib/exim4/config.autogenerated
     You are using the debianized configuration scheme - with either
     'split' or 'unsplit' configuration file.
 	See the 'DEBIANIZED' section below.
 HAND-CRAFTED
 ------------
 Use 'grep "local_scan_path" /etc/exim4/exim4.conf" to see if the sa-exim
 line is included in the configuration. If grep returns something, check
 if it matches the following line. If grep returns nothing, you have to
 manually add the following line to the exim4.conf file and restart exim4.
     local_scan_path = /usr/lib/exim4/local_scan/sa-exim.so
 Change or add the line above and manually restart exim4 by issuing
 'invoke-rc.d exim4 reload' or '/etc/init.d/exim4 reload' as root.
 DEBIANIZED
 ----------
 Use 'grep "local_scan_path" /var/lib/exim4/config.autogenerated' to
 see if the sa-exim line is included in the configuration. If grep
 returns something, you're set and already using the sa-exim module. If
 grep returns nothing, we need to figure out a few things:
 Issue:
 	$ grep "use_split_config" /etc/exim4/update-exim4.conf.conf
       dc_use_split_config='true'
 If your result shows 'false' where mine shows 'true', then you're
 using the unsplit configuration, generated from
 /etc/exim4/exim4.conf.template.  If you haven't customized that file
 you could edit /etc/exim4/update-exim4.conf.conf by hand, change the
 'false' to 'true' and issue 'update-exim4.conf' as root. Then, check
 again if the sa-exim module line is included. It should. If it still
 isn't: mail me. If it is, restart exim4 by issuing 'invoke-rc.d exim4
 restart' or '/etc/init.d/exim4 restart' as root. If you *have*
 customized /etc/exim4/exim4.conf.template, then you'd better stick
 with the unsplit configuration scheme and add the local_scan_path
 setting by hand, like with the hand-crafted configuration file.
 Next, read all about greylisting and sa-exim:
 ***************
 * GREYLISTING *
 ***************
 Notes on greylisting with sa-exim.
 If you use SpamAssassin 3.0 or better, you do not need to patch it, you
 can just use the Greylisting module shipped with sa-exim.
 The only thing you need to do to enable it, is to copy the 4 lines below
 loadplugin in the greylisting README, and adjust the score if you wish (see
-README.Greylisting for details)
+README.Greylisting for details).
+***********************************
+* PROBLEMS WITH BAYES AUTO-EXPIRY *
+***********************************
+When scanning mail during the SMTP dialogue there is somewhat limited
+time before the remote host gives up, even if they should wait for at
+least ten minutes. To avoid Exim returning a temporary error status,
-If you use a version of SA older than 3.0 (if you are, you really,
+or the remote host giving up prematurely and in some cases for good,
-really should upgrade!), you will need to patch spamassassin's sources
+SA-Exim overrides Exim's timeout handler and accepts the message if
-to support greylisting.
+SpamAssassin takes too long, by default 240 seconds.
-There are two versions of the patches:
- - /usr/share/doc/sa-exim/patches/SA-greylisting-2.4x.diff
+Using SpamAssassin's Bayesian learning module means that it will
-   This patch can be applied to versions 2.4x of SpamAssassin. Note
+automatically expire old tokens when its database has grown too large.
-   that this patch is not fully functional anymore, it is just left as
+That can take several minutes. If it takes too long, SA-Exim will
-   a template should you want to backport the current 2.6x patch.
+abort it, meaning that SpamAssassin will run auto-expiry again next
-   That said, you really ought to upgrade SA to 2.6x or 3.x
+time, and be aborted, and so on...
- - /usr/share/doc/sa-exim/patches/SA-greylisting-2.6.diff
-   This patch can be applied to versions 2.6x of SpamAssassin.
+If this happens, you have a few remedies:
-Please read README.Greylisting for more information on how to enable
-this feature, and what further changes are needed.
-Note that this configuration won't be supported in the future, and you
+) Set SAtimeout to a higher value in /etc/exim4/sa-exim.conf.
-are encouraged to upgrade to SA 3.0 or better.
-*************
+) Run sa-learn --force-expire periodically. How you run it depends on
-* BE WARNED *
+   how you've configured SpamAssassin. Running it as Debian-exim may
-*************
+   be sufficient.
-By applying these patches, you change the sourcecode of SpamAssassin
-(again, this is if you use a version of SpamAssassin earlier than 3.0)
-This also means that when the SpamAssassin package gets upgraded, the
-changes made by the patch are LOST.
-This *MIGHT* cause your mail setup to break. It might be best to put
-SpamAssassin on hold:
+a) In addition, you can add
-  $ echo "spamassassin hold" | dpkg --set-selections
+   bayes_auto_expire 0
+   to /etc/spamassassin/local.cf. This may not be a good idea if
+   SpamAssassin, for whatever reason, is also used as a more
+   traditional filter from e.g. .procmailrc, as all users will need to
-You can later set it to install again with:
+   run sa-learn --force-expire then.
-  $ echo "spamassassin install" | dpkg --set-selections
+b) If you get a lot of mail, consider adding
+   bayes_learn_to_journal 1
+   to local.cf. See the Mail::SpamAssassin::Conf(3) manual page for
+   more information.
 **********************************
 * NOTICE ABOUT SPAMC CONFIG FILE *
 **********************************
 Recent versions of spamc can read command-line parameters and switches
 from a configuration file called /etc/spamassassin/spamc.conf. If that
 file specifies conflicting options, it will prevent SA-Exim from
 working. For now, you'll have to make sure that it doesn't.
+ -- Magnus Holmgren <holmgren@debian.org>, Tue, 24 Jun 2008 14:27:59 +0200

Subversion Repositories

(root)/trunk/debian/README.Debian @ 64 - Rev 6 → 46