This plugin hasn’t been tested with the latest 3 major releases of WordPress. It may no longer be maintained or supported and may have compatibility issues when used with more recent versions of WordPress.

Defensio Anti-Spam


Defensio is an advanced spam filtering web service that learns and adapts to your behaviors and those of your users.
In addition to simple spam filtering, we also provide world-class malicious content detection, profanity filtering,
URL categorization, script detection and much more.

Advanced features such as support for OpenID, detailed statistics, charts and counter widget are also available.

Defensio aims to be an all-in-one anti-spam solution. Therefore, using it along with other anti-spam plugins WILL
cause problems. PLEASE deactivate Akismet and other similar plugins before activating Defensio.

OpenID Support

If you wish to enable OpenID support, you must also install another plugin called WP-OpenID. It can be found at

Spread the Defensio Love!

Love Defensio? Spread the word by featuring how many spam comments Defensio filtered with the Defensio Counter!

If your WordPress theme supports widgets, simply add the Defensio Counter widget to your sidebar. You can set color
and alignment options.

If your theme does NOT support widgets, all hope is not lost. You can simply edit your ‘sidebar.php’ file and add
the following code snippet where you want the counter to appear:

By default, the counter is dark grey and left aligned. However, you can customize your counter by passing arguments
as follow:

You can replace ‘color’ by ‘dark’ or ‘light’ and you can replace ‘align’ by ‘left’, ‘right’, ‘center’.

If you are familiar with basic image manipulation, CSS and HTML, you’ll find it very easy to create your very own
Defensio counter. To do so, you only need to modify lib/defensio_counter.php and put a custom .gif image file in
the images directory. Be careful to follow the naming convention we already have in place.


Defensio does not work with WordPress 2.9 due to a known WordPress bug (
This bug has been fixed in WordPress 2.9.1, so make sure to update your installation before using Defensio.

PHP 5 is also required. This plugin will NOT work with PHP 4.

Need Help?

Visit our helpdesk at


  • The standard Defensio Quarantine view, sorted and color-coded by spaminess.

  • The recent accuracy chart.

  • Advanced settings.


  1. IMPORTANT: Deactivate Akismet and/or any other anti-spam plugins by going to your Plugins tab in the WordPress
    control panel. Simply click “deactivate” to deactivate the desired plugins.

    Using multiple spam-filtering solutions will negatively impact Defensio’s performance.

    Note: If are upgrading from an older version of Defensio, please deactivate the old plugin before proceeding with
    the upgrade. Moreover, please delete the old Defensio plugin directory from your server. Not doing so could lead
    to version conflicts.

  2. Copy the ‘defensio-anti-spam’ folder (unzipped from the file you downloaded) into ‘wp-content/plugins/’. You
    should now have a file called ‘defensio.php’ in ‘wp-content/plugins/defensio-anti-spam/’.

  3. Return to the Plugins tab in your control panel and activate Defensio.

  4. Under the Plugins tab, you will find a new tab called Defensio Configuration. Go there and enter your API key.
    If the key turns green, this means it has been successfully validated. If you don’t have an API key, you can
    obtain one for free at

    Under Defensio Configuration, you may also set the threshold level for “obvious spam” (this can be hidden from
    your spambox, at your option). We recommend you leave this “obvious spam” level at its default value (80%) until
    you get a feel for what a better value might be for your own purposes. You may also choose to enable automatic
    deletion of spam on old articles, though we do do not recommend this by default.

    Note: If you’re upgrading from an older version of Defensio, the API key should be pre-populated for you.

  • Your blog is now protected by Defensio’s enhanced spam filtering web service. From now on, all comments posted
    to your blog will be analyzed by Defensio and attributed a “spaminess” value that will help you sort and manage
    your Quarantine. Under your blog’s Comments tab, notice that the quarantine has been re-labelled “Defensio Spam”.
    Go there experience the Defensio goodness first-hand.


Visit our FAQ at

Contributors & Developers

“Defensio Anti-Spam” is open source software. The following people have contributed to this plugin.

Translate “Defensio Anti-Spam” into your language.

Interested in development?

Browse the code, check out the SVN repository, or subscribe to the development log by RSS.


2.7.0 (12-07-2011)

  • Official support for WordPress 3.3

2.6.2 (11-01-2011)

  • Official support for WordPress 3.2.1

2.6.1 (02-14-2011)

  • Fix missing file bug that prevented activation of the plugin

2.6.0 (02-14-2011 — Valentine’s Day)

  • Official support for WordPress 3.1
  • Misc minor bug fixes

2.5.9 (08-30-2010)

  • Fixed “malicious content detection not enabled” bug in stats
  • Fixed bug that broke some multi-site installations

2.5.8 (07-07-2010)

  • Fixed a problem that only affected new users on WP 3.0
  • Fixed name clash with PEAR

2.5.7 (06-30-2010)

  • Fixed mysteriously disappearing API keys

2.5.6 (06-30-2010)

  • Fixed an important bug that caused invalid requests to be sent to Defensio under WordPress 3.0

2.5.5 (06-17-2010)

  • Fixed bug causing a PHP crash on some configurations
  • A few minor fixes
  • Support for WordPress 3.0

2.5.4 (unreleased)

  • Moved CHANGELOG.txt to readme.txt for better compatibility

2.5.3 (01-14-2010)

  • Fixed bug causing admins to sometimes being notified of spam by email

2.5.2 (01-14-2010)

  • Fixed comment deletion bug

2.5.1 (01-13-2010)

  • Fixed bug that prevented plugin from working on MU

2.5.0 (01-12-2010)

  • Initial release supporting Defensio 2.0