an enhanced bayesian-type spam filter for Communigate Pro™

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According to recent statistics, 90% to 95% of all e-mail on the Internet is spam, and that 90% equates to productive time lost for everyone involved. Not to mention all of the man-hours lost by your employees having to take the time to filter through and delete them. You need a solution. But, you were already convinced of that before you visited this site.

PolluStop can be a large part of that solution.

PolluStop identifies spam before it gets to the user's mailbox. Spam can be passed through to the end user (with or without being marked as such), discarded, redirected to a special folder where it is stored with other spam candidates, or even stored in the postmaster's mailbox for further evaluation. You can do whatever you want to with spam; PolluStop assists your decision-making process by marking all messages according to their contents.

PolluStop determines that an e-mail is spam via a multi-tiered approach:

  • First, by using known statistics. PolluStop uses a dictionary of keywords previously encountered in pre-sorted e-mail (the initial training set) to measure the number of occurrences of each of those words in incoming e-mails.
  • Second, by establishing a diagnostic routine. Using the statistical data acquired in tier one, PolluStop establishes its own diagnostic routine based on its confidence regarding an e-mail's validity.
  • Third, a set of admin-configurable rules and high-level pattern matching. This breaks down spammers' attempts to circumvent the statistical approach.
  • Finally, regular expressions and OCR (when enabled) will identify the more aggressive messages that may have gotten that far
  • Along the way, various levels of user-configurable blacklists and whitelist will bypass PolluStop processing and will make the message end up at the correct location

PolluStop 1.0 was a large Perl-based script that provided amazing results for over two years (considering Perl's inherent speed limitations).

PolluStop 2.0 has been rebuilt (based upon its original algorithms) using compiled languages and the result is an amazingly fast application that is capable of processing e-mail at more than 100 times the speed of its predecessor (it is capable of scanning more than 100 e-mails per second - results may vary depending upon your server hardware).

PolluStop 2.1 offers a new set of spam-fighting rules, a new set of web-based configuration windows, a new database system that is faster than ever before, and other new features that have never been seen before, features that are PolluStop exclusives.

PolluStop 2.2 offers auto-updates, a new set of three spam-fighting rules such as message date analysis and split subjects detection, and its core modules have been partially rewritten for consistency and speed.

PolluStop 2.3 offers automatic whitelist / blacklisting capabilities.

PolluStop 2.4 offers per-user whitelist and other settings, image recognition, and session-based web administration easy to integrate within CGP webmail system.

PolluStop 2.5 offers secure access (SSL / HTTPS) to the web administration, custom regex-based rules, and protection against attachment spam

PolluStop 2.6 offers reliable client-controller model for cluster-based installations

PolluStop 2.7 offers per-domain white and blacklisting, tighter integration with the CGP access rights and more performance regarding white/blacklisting

PolluStop 2.8 offers daily reports to the postmaster, as well as more reporting concerning some of its internals, to help the administrators tweak its performance to the best levels

PolluStop 2.9 offers a shared regular expression database managed by Niversoft, support for https proxying, outbound monitoring

PolluStop 2.10 offers new outbound monitoring options and discovery of known conversations

PolluStop 2.11 offers largely-increased performance with several core modules rewritten

PolluStop 2.12 offers "wildcard" domain whitelisting, performance enhancements

PolluStop's Features:

  • PolluStop is built for CommuniGate Pro
  • PolluStop uses enhanced Bayesian spam filtering. The basic Bayesian-type approach plus added algorithms, rules, regular expressions and high-level pattern matching help PolluStop to avoid false positives and also reduces the chance of false negatives
  • PolluStop protects you against anti-bayesian attacks such as HTML comments, scrambled words, accents and replacement characters to "hide" words, word separators and invisibility tags.
  • PolluStop puts its diagnostic in the e-mail headers for easy discrimination with rules.
  • PolluStop can also add a prefix to the Subject line when a threshold score is reached.
  • PolluStop can receive on-the-fly training via several methods:
    • Users can report filtering errors to a special email address.
    • Users can drop messages in special shared drop mailboxes
    • Admins can drop message files in filesystem drop directories
    • Admins can use the terminal or the webadmin interface to teach PolluStop with additional messages without stopping the filter.
  • PolluStop integrates seamlessly with CGPro.
  • PolluStop is fast (it can process more than 100 messages per second, depending upon your server hardware)
  • PolluStop contains an Attached File Identifier (see Find Attachments Filter)
  • All PolluStop filtering parameters are admin-modifiable if needed and accessible from the web interface.
  • PolluStop has internal timeouts to help prevent problems caused by badly formatted, very long messages that could choke it.
  • PolluStop automatically differentiates between which messages to scan and not to scan (resolution of account aliases, domain aliases and router entries).
  • PolluStop decodes base-64 and quoted-printable encoded text. It can also filter several character sets; this feature allows it to be usable with non-ANSI character-based languages.
  • PolluStop can parse both mdir and mbox-type mailboxes.
  • PolluStop performs both token polymorphism and contextual token identification. This allows more accurate scoring.
  • PolluStop is multithreaded. Drop mailbox and http processing will not delay its normal filtering process.
  • PolluStop is available on multiple platforms. The currently supported platforms Windows Win7/Server 2008, Linux, MacOS 10.7+, FreeBSD 8+, all on x64 architecture. x86 and Solaris builds are discontinued due to lack of demand.
  • It is also possible to run PolluStop on OpenBSD-i386, and should be possible to run it on many other i386 platforms providing an emulation layer.
  • PolluStop comes packaged with a spam database that was pre-trained from several hundred real spam messages received from multiple sources over a substantial period of time.
  • PolluStop automatically sends an e-mail to the Postmaster when an internal problem occurs, such as a license timeout or when a limit is reached. Its license contains a built-in grace period.
  • PolluStop uses global, per-domain and per-user whitelists and blacklists of Return-path, From and List-ID headers. Single addresses or whole domains can be blacklisted, and these lists can be automatically populated by the e-mails reported for training
  • (v2.1) PolluStop can be configured easily via an intuitive web interface
  • (v2.1) PolluStop logs statistics on all scanned messages. These statistics logs are available from the web interface.
  • (v2.1) PolluStop can remember all outbound messages; all inbound messages that are direct replies to sent messages will never be treated as spam, whatever their content.
  • (v2.1) PolluStop uses a compact and very fast database library for both the tokens and the remembered message IDs.
  • (v2.2) PolluStop web interface includes a "check for new version" and can be updated to the new version in two clicks!
  • (v2.2) PolluStop detects split words in Subject field
  • (v2.3) View-only mode for the administration pages
  • (v2.3) PolluStop can whitelist based on or single words in the headers or message body
  • (v2.4) PolluStop can read most text in images (OCR), allowing to protect against image spam
  • (v2.4) PolluStop can remember all e-mail addresses to which an email has been sent and store them in the user's whitelist
  • (v2.4) PolluStop has session-based web administration, compatible with CGP's webmail, allowing to easily integrate the per-user settings page into a CGP webmail skin.
  • (v2.5) PolluStop offers secure access (SSL / HTTPS) to the web administration
  • (v2.5) PolluStop runs on x64 architecture
  • (v2.5) PolluStop allows admin-configured regular expression to be installed, which, when they apply on a message, will modify its final score
  • (v2.6) PolluStop offers a reliable client-controller model for cluster-based installations, making it a good choice for all sizes of CGP servers
  • (v2.7) PolluStop uses a sqlite3 database for user settings, white/blacklists and conversations IDs
  • (v2.8) PolluStop generates daily report to the postmaster with helpful information about usage, performance, spam sources and targets.
  • (v2.9) PolluStop periodically downloads a shared regular expressions database managed to Niversoft to help circumvent a few more types of spam.


PolluStop is licensed on a per-account basis. PolluStop reports the minimal number of accounts needed in the license according to its current settings (via the web interface).

You can request a free 60-day trial license. Only one trial license needs to be issued (by main domain name) per Communigate Pro™ server. Please include the exact Communigate Pro™ main domain name in your request. You can request one trial license for each of your servers, but these licenses will be concurrent in time. Trial licenses are not limited in any other way (unlimited accounts, unlimited message flow).

A full license includes:

  • No traffic limit
  • No expiration (in fact, it expires on December 31, 2999)
  • All minor upgrades (bug fixes, optimizations, minor enhancements)
  • One month of Support

With your license purchase, one month of support is included for free. Once this month has passed, you can continue support by subscribing to our extended support package. Extended support is available for 15% of your current license price per year.

Support includes:

  • All upgrades, major and minor
  • Support for installation, training and other issues, via E-mail or IM


Sample Prices

The following table gives you the license costs depending on the number of users. Enter the size of the license you require in the last row to get a maximum exact price. Please contact Niversoft for an official quote. The prices are fixed in CAD but displayed in USD according to the current exchange rate, updated daily.

Accounts Cost per Account License Total Support / year Total

Please contact Niversoft to request your trial license.

To to get a license quote, to get an invoice processed, or to purchase now, please continue to the Purchases page.

Download PolluStop v2.14.2e : [HISTORY]

Without a valid license, PolluStop will filter only the first five e-mails that pass through it. All others will not be scanned.

Updating to a new version is easy, simply follow the instructions in the provided INSTALL or UPGRADE files.

Continue to the Download page...