spampd is an SMTP/LMTP proxy that marks (or tags) spam using
SpamAssassin (http://www.SpamAssassin.org/). The proxy is designed
to be transparent to the sending and receiving mail servers and at no point
takes responsibility for the message itself. If a failure occurs within
spampd (or SpamAssassin) then the mail servers will disconnect and the
sending server is still responsible for retrying the message for as long
as it is configured to do so.
spampd uses SpamAssassin to modify (tag) relayed messages based on
their spam score, so all SA settings apply. This is described in the SA
documentation. spampd will by default only tell SA to tag a
message if it exceeds the spam threshold score, however you can have
it rewrite all messages passing through by adding the --tagall option
(see SA for how non-spam messages are tagged).
spampd logs all aspects of its operation to syslog(8), using the
mail syslog facility.
Time::HiRes (not actually required but recommended)
spampd is meant to operate as an S/LMTP mail proxy which passes
each message through SpamAssassin for analysis. Note that spampd
does not do anything other than check for spam, so it is not suitable as
an anti-relay system. It is meant to work in conjunction with your
regular mail system. Typically one would pipe any messages they wanted
scanned through spampd after initial acceptance by your MX host.
This is especially useful for using Postfix's (http://www.postfix.org)
advanced content filtering mechanism, although certainly not limited to
Please re-read the second sentence in the above paragraph. You should NOT
enable spampd to listen on a public interface (IP address) unless you
know exactly what you're doing! It is very easy to set up an open relay this
Here are some simple examples (square brackets in the ``diagrams'' indicate
Running between firewall/gateway and internal mail server
The firewall/gateway MTA would be configured to forward all of its mail
to the port that spampd listens on, and spampd would relay its
messages to port 25 of your internal server. spampd could either
run on its own host (and listen on any port) or it could run on either
mail server (and listen on any port except port 25).
Internet -> [ MX gateway (@inter.net.host:25) ->
spampd (@localhost:2025) ] ->
Internal mail (@private.host.ip:25)
Using Postfix advanced content filtering
Please see the FILTER_README that came with the Postfix distribution. You
need to have a version of Postfix which supports this (ideally v.2 and up).
Internet -> [ Postfix (@inter.net.host:25) ->
spampd (@localhost:10025) ->
Postfix (@localhost:10026) ] -> final delivery
Note that these examples only show incoming mail delivery. Since it is
usually unnecessary to scan mail coming from your network (right?),
it may be desirable to set up a separate outbound route which bypasses
If upgrading from a version prior to 2.2, please note that the --add-sc-header
option is no longer supported. Use SAs built-in header manipulation features
instead (as of SA v2.6).
Upgrading from version 1 simply involves replacing the spampd program file
with the latest one. Note that the dead-letters folder is no longer being
used and the --dead-letters option is no longer needed (though no errors are
thrown if it's present). Check the ``Options'' list below for a full list of new
and deprecated options. Also be sure to check out the change log.
spampd can be run directly from the command prompt if desired. This is
useful for testing purposes, but for long term use you probably want to put
it somewhere like /usr/bin or /usr/local/bin and execute it at system startup.
For example on Red Hat-style Linux system one can use a script in
/etc/rc.d/init.d to start spampd (a sample script is available on the
spampd Web page @ http://www.WorldDesign.com/index.cfm/rd/mta/spampd.htm).
The options all have reasonable defaults, especially for a Postfix-centric
installation. You may want to specify the --children option if you have an
especially beefy or weak server box because spampd is a memory-hungry
program. Check the ``Options'' for details on this and all other parameters.
Note that spampdreplacesspamd from the SpamAssassin distribution
in function. You do not need to run spamd in order for spampd to work.
This has apparently been the source of some confusion, so now you know.
Here is a typical setup for Postfix ``advanced'' content filtering as described
in the FILTER_README that came with the Postfix distribution (which you
really need to read):
smtp inet n - y - - smtpd
localhost:10026 inet n - n - 10 smtpd
The first entry is the main public-facing MTA which uses localhost:10025
as the content filter for all mail.The second entry receives mail from
the content filter and does final delivery. Both smtpd instances use
the same Postfix main.cf file. spampd is the process that listens on
localhost:10025 and then connects to the Postfix listener on localhost:10026.
Note that the "myhostname" options must be different between the two instances,
otherwise Postfix will think it's talking to itself and abort sending.
For the above example you can simply start spampd like this:
FILTER_README from the Postfix distro has more details and examples of
various setups, including how to skip the content filter for outbound mail.
Another tip for Postfix when considering what timeout values to use for
--childtimout and --satimeout options is the following command:
"# postconf | grep timeout"
This will return a list of useful timeout settings and their values. For
explanations see the relevant "man" page (smtp, smtpd, lmtp). By default
spampd is set up for the default Postfix timeout values.
--host=ip[:port] or hostname[:port]
Specifies what hostname/IP and port spampd listens on. By default, it listens
on 127.0.0.1 (localhost) on port 10025.
Important! You should NOT enable spampd to listen on a
public interface (IP address) unless you know exactly what you're doing!
Specifies what port spampd listens on. By default, it listens on
port 10025. This is an alternate to using the above --host=ip:port notation.
--relayhost=ip[:port] or hostname[:port]
Specifies the hostname/IP where spampd will relay all
messages. Defaults to 127.0.0.1 (localhost). If the port is not provided, that
defaults to 25.
Specifies what port spampd will relay to. Default is 25. This is an
alternate to using the above --relayhost=ip:port notation.
--user=username or --u=username
--group=groupname or --g=groupname
Specifies the user and group that the proxy will run as. Default is
--children=n or --c=n
Number of child servers to start and maintain (where n > 0). Each child will
process up to --maxrequests (below) before exiting and being replaced by
another child. Keep this number low on systems w/out a lot of memory.
Default is 5 (which seems OK on a 512MB lightly loaded system). Note that
there is always a parent process running, so if you specify 5 children you
will actually have 6 spampd processes running.
You may want to set your origination mail server to limit the
number of concurrent connections to spampd to match this setting (for
Postfix this is the "xxxx_destination_concurrency_limit" setting where
'xxxx' is the transport being used, usually 'smtp', and the default is 100).
spampd works by forking child servers to handle each message. The
maxrequests parameter specifies how many requests will be handled
before the child exits. Since a child never gives back memory, a large
message can cause it to become quite bloated; the only way to reclaim
the memory is for the child to exit. The default is 20.
This is the number of seconds to allow each child server before it times out
a transaction. In an S/LMTP transaction the timer is reset for every command.
This timeout includes time it would take to send the message data, so it should
not be too short. Note that it's more likely the origination or destination
mail servers will timeout first, which is fine. This is just a ``sane'' failsafe.
Default is 360 seconds (6 minutes).
This is the number of seconds to allow for processing a message with
SpamAssassin (including feeding it the message, analyzing it, and adding
the headers/report if necessary).
This should be less than your origination and destination servers' timeout
settings for the DATA command. For Postfix the default is 300 seconds in both
cases (smtp_data_done_timeout and smtpd_timeout). In the event of timeout
while processing the message, the problem is logged and the message is passed
on anyway (w/out spam tagging, obviously). To fail the message with a temp
450 error, see the --dose (die-on-sa-errors) option, below.
Default is 285 seconds.
--pid=filename or --p=filename
Specifies a filename where spampd will write its process ID so
that it is easy to kill it later. The directory that will contain this
file must be writable by the spampd user. The default is
--logsock=unix or inet "(new in v2.20)"
Syslog socket to use. May be either ``unix'' of ``inet''. Default is ``unix''
except on HP-UX and SunOS (Solaris) systems which seem to prefer ``inet''.
--nodetach "(new in v2.20)"
If this option is given spampd won't detach from the console and fork into the
background. This can be useful for running under control of some daemon
management tools or when configured as a win32 service under cygrunsrv's
The maximum message size to send to SpamAssassin, in KBytes. By default messages
over 64KB are not scanned at all, and an appropriate message is logged
indicating this. The size includes headers and attachments (if any).
Acronym for (d)ie (o)n (s)pamAssassin (e)rrors. By default if spampd
encounters a problem with processing the message through Spam Assassin (timeout
or other error), it will still pass the mail on to the destination server. If
you specify this option however, the mail is instead rejected with a temporary
error (code 450, which means the origination server should keep retrying to send
it). See the related --satimeout option, above.
--tagall or --a
Tells spampd to have SpamAssassin add headers to all scanned mail,
not just spam. By default spampd will only rewrite messages which
exceed the spam threshold score (as defined in the SA settings). Note that
for this option to work as of SA-2.50, the always_add_report and/or
always_add_headers settings in your SpamAssassin local.cf need to be
set to 1/true.
--log-rules-hit or --rh
Logs the names of each SpamAssassin rule which matched the message being
processed. This list is returned by SA.
--set-envelope-headers or --seh "(new in v2.30)"
Turns on addition of X-Envelope-To and X-Envelope-From headers to the mail
being scanned before it is passed to SpamAssassin. The idea is to help SA
process any blacklist/whitelist to/from directives on the actual
sender/recipients instead of the possibly bogus envelope headers. This
potentially exposes the list of all recipients of that mail (even BCC'ed ones).
Therefore usage of this option is discouraged.
NOTE: Even though spampd tries to prevent this leakage by removing the
X-Envelope-To header after scanning, SpamAssassin itself might add headers
itself which report one or more of the recipients which had been listed in
--set-envelope-from or --sef "(new in v2.30)"
Same as above option but only enables the addition of X-Envelope-From header.
For those that don't feel comfortable with the possible information exposure
of X-Envelope-To. The above option overrides this one.
--auto-whitelist or --aw
This option is no longer relevant with SA version 3.0 and above, which
controls auto whitelist use via local.cf settings.
For SA version < 3.0, turns on the SpamAssassin global whitelist feature.
See the SA docs. Note that per-user whitelists are not available.
--local-only or --L
Turn off all SA network-based tests (DNS, Razor, etc).
--config=filename or --C filename
Use the specified filename as the config read by spampd in addition to
SpamAssassin's normal configuration files, overriding the latter. Defaults
to not using a spampd specific configuration file.
Use the specified directory as home directory for the spamassassin process.
Defaults to /var/cache/spampd.
--debug or --d
Turns on SpamAssassin debug messages which print to the system mail log
(same log as spampd will log to). Also turns on more verbose logging of
what spampd is doing (new in v2). Also increases log level of Net::Server
to 4 (debug), adding yet more info (but not too much) (new in v2.2).
--help or --h
Prints usage information.
The following options are no longer used but still accepted for backwards
compatibility with prevoius spampd versions:
Running between firewall/gateway and internal mail server
spampd listens on port 10025 on the same host as the internal mail server.
Same as above but spampd runs on port 10025 of the same host as
the firewall/gateway and passes messages on to the internal mail server
on another host.
Using Postfix advanced content filtering example and the SA auto-whitelist feature
spampd v2 uses two Perl modules by Bennett Todd and Copyright (C) 2001 Morgan
Stanley Dean Witter. These are distributed under the GNU GPL (see
module code for more details). Both modules have been slightly modified
from the originals and are included in this file under new names.
spampd v1 was based on code by Dave Carrigan named assassind. Trace
amounts of his code or documentation may still remain. Thanks to him for the
original inspiration and code. See http://www.rudedog.org/assassind/ .
Various people have contributed patches, bug reports, and ideas, all of whom
I would like to thank. I have tried to include credits in code comments and
in the change log, as appropriate.
Code Contributors (in order of appearance):
Copyright, License, and Disclaimer
spampd is Copyright (c) 2002 by World Design Group, Inc. and Maxim Paperno.
Portions are Copyright (C) 2001 Morgan Stanley Dean Witter as mentioned above
in the Credits section.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
The GNU GPL can be found at http://www.fsf.org/copyleft/gpl.html
Figure out how to use Net::Server::PreFork because it has cool potential for
load management. I tried but either I'm missing something or PreFork is
somewhat broken in how it works. If anyone has experience here, please let
Add configurable option for rejecting mail outright based on spam score.
It would be nice to make this program safe enough to sit in front of a mail
server such as Postfix and be able to reject mail before it enters our systems.
The only real problem is that Postfix will see localhost as the connecting
client, so that disables any client-based checks Postfix can do and creates a
possible relay hole if localhost is trusted.