Enable SPAM Protection on your Wordpress MU website.
Be advised that WordPress 2.9 MU is no longer a separate project from the main WordPress branch. It is continuing development as part of the main WordPress 3 branch under the name ‘multi-site’ or MS. This means that you can get all the benefits of both WordPress and WordPress MU versions by using the latest WordPress version. To help you in the process of creating a multi-user website with the latest WordPress version we have created a detailed step by step WordPress multi-site tutorial available here.
In order to protect your blog from spam comments you may use one of the most powerful anti spam systems – Akismet. You can install Akismet plugin via your admin area -> Plugins -> Add new:
After you click on the Search button you will be displayed with a list of plugins that you can install:
By clicking on the Install button you will a new window will be displayed with some general information for this plugin. You may proceed with the installation by clicking on the Install now button.
When the installation is completed you can activate your plugin via the activation link:
As soon as you have the plugin activated you will need to enter your WordPress.com API Key:
You can receive a WordPress.com API Key in just a few seconds by registering at: https://en.wordpress.com/signup/ Please use your real email address for the sign up where you will receive the API key. When you receive your API key you may enter it on the Akismet configuration page of your WordPress:
If you would like to start your WordPress MU Blog in a few clicks, check the WordPress MU Hosting package.