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.


This plugin protects your WPMU signup process against spambots with a simple math question. This plugin is based on the Block-Spam-By-Math plugin created by Alexander Grau. This only protects the new blog creation process and the new user creation process. If you wish to have individual blog protection use the regular Block-Spam-By-Math plugin on individual blogs.


For additional help check the plugin page at:


  • Sample WPMU sign-up screen.


  1. Download and extract the zip file, upload the wpmu-block-spam-by-math.php to your wp-content/mu-plugins directory

Visit the plugin page ( to see more about it.


Does this plugin work with the regular Block spam By Math plugin?

Yes, you can run both. I use the regular WordPress plugin on my WPMU site as well to allow individual site owners the option to add the protection at the blog level.

Does this plugin work on regular WordPress?

No. This is only targeting the WPMU new blog signup and new user signup functions. If you need WP registration, login and comment protection I recommend you get the Block Spam By Math plugin.

Can I change the math questions?

Yes, just edit the two rand functions in the plugin file to generate whatever type of numbers you want.

Does this plugin work on regular Buddypress?

Yes. Requires Buddypress 1.2.7 or higher


There are no reviews for this plugin.

Contributors & Developers

“WPMU Block Spam By Math” is open source software. The following people have contributed to this plugin.



  • V1.00: Initial release. [Jan 4, 2010]
  • V1.10: Added compatibility with Buddypress default theme (** See note under Installation)
  • V1.2: Updated to work with Buddypress 1.2.3
  • V1.3: Updated to work with Buddypress 1.2.7