Something for your 'Where SpamAssassin Is Used' page
Mark
Announcing amavisd-new-20020517, the SpamAssassin edition
=========================================================
May 17, 2002
Available at:
http://www.ijs.si/software/amavisd/
amavisd-new-20020517 is primarily a response to popular demand for
Mail::SpamAssassin support. If amavisd-new-20020224 meets your needs,
there is no urgent need to upgrade. There are no incompatible changes
between these two versions, except some new (optional) amavisd.conf
variables, so you may keep old amavisd.conf file if you wish.
A new file README.exim is now provided, so that Exim 4.x is now a
supported and tested configuration, besides the usual Postfix and
sendmail/milter MTAs. Also included is a brand new qmail amavis client
by Lars Hecking (untested, please try it), plus his updated version of
amavis.c (no longer needed in recommended Postfix and Exim configurations,
and Sendmail milter and qmail configurations use a different client).
Several files are unchanged from the base amavisd CVS release 2002-05-13
and do not reflect the amavisd-new state: FAQ, HINTS, INSTALL, BUGS,
NEWS, TODO, ChangeLog, tests/, doc/. Please start with this file
README.amavisd-new-RELNOTES and follow it. More recent instructions
and last-minute changes are available from the web page.
Changes since amavisd-new-20020224:
- supports Mail::SpamAssassin and Vipul's Razor (1.20 required)
for spam checking (but not for modifying mail body - only add headers
and/or address extension, or reject/discard/quarantine spam).
NOTE: spam checks are off in the default amavisd setup.
Copy file ./amavis/amavisd.in.all to ./amavis/amavisd.in
before running ./configure and make, to use the
spam-check-enabled version!
Amavisd calls Mail::SpamAssassin directly, avoiding the need to set up
spamc/spamd or to chain filters. This is more efficient, one daemon
less to worry about, although maybe less flexible for some taste.
At the moment the SA per-user database is not used. Feel free to
experiment with it and let me know what you came up with.
The usual SA config files are observed, but remote tests are disabled
by default (Razor is handled directly, RBL lookups can/should be
performed early by MTA which knows from what IP address mail came,
and that information is (mostly) lost afterwards). If you feel otherwise,
change the hard-wired settings in the call:
$spamassasin_obj = Mail::SpamAssassin->new(
{ dont_copy_prefs => 1, local_tests_only => 1 } )
(also the Razor score contribution is hard-wired,
modify: '$razor_spam_found ? 3 : 0' to will).
Amavisd-new handles Razor checks directly to be able to exercise
more control over it than would otherwise be available through SA:
timing, signatures are needed for insertion into header, skips one-liner
body checks which are common Razor false-positives. To avoid SA calling
Razor again, either keep the default setting 'local_tests_only=>1',
or set 'score RAZOR_CHECK 0' in the SA configuration.
Added are 'whitelist_sender' hash and ACL lookups (see README.lookups),
which approves spam from specified SMTP originator addresses (SpamAssassin
can only check and whitelist rfc822 headers, not the envelope addresses,
and I see no way of passing envelope addresses to it - which is a pitty,
as important information is lost.
SpamAssassin checks are computationally quite expensive compared to other
amavisd activities, and the time needed for SA check goes up significantly
with the message size. SA check are skipped (but not the Razor check)
if mail size exceeds 64k. My analysis shows that presently less than 1%
of spam exceeds 64k characters, and this is probably well below the
false-negative SA rate, so it is not worth wasing time to check large mail.
remaining changes:
- new file README.exim (thanks to Jochen Erwied, Patrice Fournier
and Igor D'Astolfo);
- updated README.postfix to describe how to avoid running header_checks,
body_checks and dns_lookups in Postfix twice;
- put back file README.customize, which was omitted from amavisd-new-20020224
by mistake (but available with previous version and on the web);
- added introductory paragraph to README, the rest still needs to be updated;
- added missing last-step check for '.' in hash lookups to match examples
and make it more useful;
- added timeouts to certain tasks to make it better suitable for unattended
operation (less, but still subject to certain DoS attacks, similar to
the official amavisd). The main reason for adding timeouts is that we
don't want spam checking to slow down amavisd operation too much: if it
takes too long, just skip it (assume not spam) and move on;
- change unmangle_sender() to believe sender address for Klez viruses;
this is sometimes wrong, but seems like people prefer to sacrifice
few false accusations in favour of some warranted sender notifications.
Feel free to hack this routine at will (and publish good ideas),
it is intended to be modified;
- use Perl module Errno instead of errno.ph to avoid using broken
file errno.ph on some popular platforms;
- make possible to have per-sender-domain administrator e-mail address
for admin notifications (hash lookup %mailto, sub warn_admin() )
- relax temporary file/dir protection to allow them to be readable
by the group. This makes possible for anti-virus (daemon) checker
to run under a different user (but in the same group). This should
be safer as it makes impossible for virus-checking daemon to clobber
files. This is only supported in the all-SMTP configuration. To use
it with traditional amavis clients (e.g. milter), you will have to
modify their sources to change umask and mods for file/dir it creates;
- avoid changing sender address <> to <""> under certain circumstances
(not strictly wrong, but still a bad idea);
- replaced header 'X-Razor-Warning:' with SA-compatible 'X-Spam-Status:' ;
the 'X-Razor-id:' is still provided to facilitate user spam reporting;
- added '--' between options and argument when calling $sendmail_wrapper
to be triply sure we avoid problems with some mailers (note that
$sendmail_wrapper is only still needed in the sendmail setup,
Postfix and Exim do not need it in the recommended configuration);
- tidy the %local_delivery_aliases mechanism for local delivery / quarantine;
- allow MIME::Parser to decode uuencoded parts, if it feels
it can (and should) do it;
- write warnings from MIME::Parser to the log (at log level 1 or higher),
instead of discarding them.
The package is available at the usual location at:
http://www.ijs.si/software/amavisd/
where also the most up-to-date version or FAQ
and certain other fresh documentation files live.
Mark Martinec
--
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!! Mark Martinec (system manager) tel +386 1 4773-575 !!
!! J. Stefan Institute, Jamova 39 fax +386 1 2519-385 !!
!! SI-1000 Ljubljana, Slovenia [EMAIL PROTECTED] !!
!!!!!!!!!!!!!!!!!!!!!!!!!! http://www.ijs.si/people/mark/ !!!!
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