NAME
Qpsmtpd::Plugin::Quarantine - filter outbound email to prevent blacklisting
SYNOPSIS
Qpsmtpd quarantine plugin:
use Qpsmtpd::Plugin::Quarantine;
The quarantine.cgi web page:
use Qpsmtpd::Plugin::Quarantine::CGI;
main();
In crontab or nightly:
perl -MQpsmtpd::Plugin::Quarantine::Batch -e 'cronjob()'
In crontab (every five minutes?):
perl -MQpsmtpd::Plugin::Quarantine::Batch -e 'sendqueued()'
From the command line:
perl -MQpsmtpd::Plugin::Quarantine::Batch -e 'mailq()'
DESCRIPTION
Qpsmtpd::Plugin::Quarantine implements and outbound mail filter. A
substantial number of internet sites will blacklist senders if they send
too much spam. Most will do this without providing enough feedback for
you (the sender) to figure out where the spam is coming from or why you
were blacklisted.
I run ISPs and I've been blacklisted by AOL. I've been blacklisted by
Comcast. Why? Sometimes its because someone is exploting an insecure
formmail CGI on my system and sometimes its simply because I allow users
to forward email and when they do, they end up forwarding spam.
Qpsmtpd::Plugin::Quarantine understands that sometimes the sender is the
victim and sometimes not. The normal situation is that
Qpsmtpd::Plugin::Quarantine will bounce things that it thinks are spammy
back to the sender with a URL to allow the sender to push the message
onwards. However if the particular recipient is on an override list or
is very popular (maybe because someone is forwarding their mail to the
recipient or maybe they're on a mailing list) then instead of bouncing
to the sender, it will send a note to the recipient letting them know
there is a message waiting for them.
Qpsmtpd::Plugin::Quarantine will only send bounces or notifications
every so often (configurable). Both senders and recipients have the
option (via the website) to have their mail silently discarded so that
they don't get bothered again.
Qpsmtpd::Plugin::Quarantine uses OOPS to store it's persistent data in
mysql or PostgreSQL.
INSTALATION
Qpsmtpd::Plugin::Quarantine is a Qpsmtpd plugin and a web page and a
shell command and cron jobs. Installation will require some work.
Start with the standard "perl Makefile.PL" and "make install".
Prerequisites
Install Qpsmtpd. I reccomend using it with postfix. Qpsmtpd should be
the main SMTP listener. It will become your smarthost for your other
mail servers. You can relegate postfix to just handling local mail by
adding "inet_interfaces = 127.0.0.1" to it's "main.cf".
Install mysql or PostgreSQL. Provide the DBI_DSN in either
/etc/default/qpsmtpd-quarantine.pl or the Qpsmtpd plugins file (below).
Qpsmtpd plugin
Installing the Qpsmtpd plugin is easy. Create a file,
"/usr/share/qpsmtpd/plugins/quarantine" (or wherever they are) with the
following contents:
use Qpsmtpd::Plugin::Quarantine;
That's it.
In "/etc/qpsmtpd/plugins", create an entry:
#
# quarantine
#
# All of these may be set in the /etc/default/qpsmtpd-quarantine.pl. The defaults
# for these may be found in the Qpsmtpd::Plugin::Quarantine::Common module. More
# things to set can be found there too.
#
# dbi_dsn database DSN (eg: DBI:mysql:database=quarantine;host=localhost)
# username database username
# password database password
# baseurl URL of quarantine.cgi
# templates templates directory for email & web
# send_from Email address notifications are sent from
# renotify_recipient_days How often should recipients be re-notified of mail waiting (days)
# renotify_sender_ip On a per-sending-IP basis, how often should senders be renotified (days)
# notify_other_senders Should non-local senders be notified at all?
# notify_recipients How many messages should a recipient get before we prefer to notify
# the recipeint instead of the sender. Disable most sender
# notifications if 0.
# notify_recipient_only DB hash file of recipients we notify in preference to senders
#
quarantine
This should come before the Queue/delivery plugins like
"queue/postfix-queue".
/etc/default/qpsmtpd-quarantine.pl
Create a perl file, "/etc/default/qpsmtpd-quarantine.pl" to override the
defaults that can be found in the first part of the
"Qpsmtpd::Plugin::Quarantine::Common" module.
For example:
package Foobar;
use Qpsmtpd::Plugin::Quarantine::Common qw(%base_defaults);
$base_defaults{send_from} = 'quarantine-sender@out-limit.internet-mail-service.net';
/etc/qpsmtpd/recipient.special.db (optional)
This file is a Berkeley DB HASH file that should contain the email
addresses of everywhere that mail is sent on a regualar basis due to
forwarding. When these addresses are used as recipients, the recipient
will be notified in preference to the sender. Collect up all addresses
from ".forward" files, ".procmailrc" and "/etc/aliases" files from your
sytems. Dump them into a file and turn them into a DB HASH. With
postfix, this is done with the "postmap
hash:/etc/qpsmtpd/recipient.special" command.
/etc/qpsmtpd/sender.special.db (optional)
This file is a Berkeley DB HASH file that should contain the email
addresses of senders that trigger spam checking. Unless the config
parameter "check_all_recipients" is set, we won't spam-check all
messsages. This database is the set of senders which trigger a forced
spam check.
/etc/qpsmtpd/filter_domains
This file lists the domains (one per line) that we want to avoid sending
spam to. This should include AOL (aol.com aim.com cs.com netscape.net)
and Comcast (comcast.com comcast.net) at a bare minimum. This file is
required. Do not include the entire Internet (.com .net .org) as
recipients need to provide a an address that isn't in the list in order
to get their mail forwarded.
/etc/qpsmtpd/our_domains
This file lists the domains that we receive mail as. Depending on other
configuration options, we'll only bounce back to senders that are in
this list.
/etc/qpsmtpd/our_networks
This file lists the IP addresses that make up our network. Most standard
notations are recognized (eg: "216.240.40.0/25"). Depending on other
configuration options, we'll only bounce back to senders that are in
this list.
/etc/qpsmtpd/ignore_networks
Qpsmtpd::Plugin::Quarantine has a notion of what's an internal IP
address (our_networks) and what is an external IP address. This file
lists IP addresses that are neither. The list starts out with the
non-routables.
quarantine.cgi
Create a CGI somewhere. It's a very simple program:
use Qpsmtpd::Plugin::Quarantine::CGI;
main();
The URL for the CGI needs to be configured as "baseurl" in your choice
of config files.
Alternatively, you can set this up using mod_perl. Apache::Registry
provides what is needed to hook it in. The CGI remains the same.
/etc/qpsmtpd/quarantine-templates
Copy the "example-templates" directory to
"/etc/qpsmtpd/quarantine-templates". Modify as you like. All should work
as-is.
/etc/qpsmtpd/quarantine.access
This is a htpasswd-style password file that controls access to the admin
web page. Create it with "htpasswd -c /etc/qpsmtpd/quarantine.access
adminuser".
Cron jobs
Install two cron jobs:
7 7 * * * perl -MQpsmtpd::Plugin::Quarantine::Batch -e cronjob
*/10 * * * * perl -MQpsmtpd::Plugin::Quarantine::Batch -e sendqueued
Starting it up.
To fire it up, send a spammy message to a user at one of the filtered
domains. The main database will auto-initialize.
ADMINISTRATION
There is a admin web page for looking at senders and recipients. The URL
is "baseurl"/admin. Cookies must be enabled.
Qpsmtpd::Plugin::Quarantine has an internal mail queue. The following
command will dispay what's in it. Messages in quarantine are not in the
mail queue.
perl -MQpsmtpd::Plugin::Quarantine::Batch -e mailq
DEVELOPMENT STATUS
This is green code, just put into production by its author.
THANK THE AUTHOR
You can thank the author of this code by giving the author a chance to
sell you services. Either perl programming or Internet-related services
like Transit T1s, T3s, OC3s, etc. Additionally, the author is
considering offering this outgoing spam filter as a service.
Perl programming rates vary from $50/hr (working at home on something
open source that the author wanted to build anyway) to $500/hr (working
on-site in a different time zone on something proprietary).
The author runs multiple ISPs and has acess to very good pricing for
T1s, T3s, OC3s, wholesale DSL, and wholesale dialup. Please send
requests for quotes to: quarantine-rfq@trust.idiom.com.
LICENSE
This software is available with and without the GPL: please write if you
need a non-GPL license. All submissions of patches must come with a
copyright grant so that David Sharnoff remains able to change the
license at will.
Copyright(C) 2006 David Muir Sharnoff <muir@idiom.com>
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.
You should have received a copy of the GNU General Public License along
with this program; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.