For b2evolution v5.
This plugin allows you to use the GeoIP database from MaxMind to determine in which country users are located in.
Category: "Antispam Plugins"
This plugin allows you to use SpamAssassin to get Spam karma for comments.
Categories: Antispam Plugins, 2.x & above, 3.x (incomplete list), 4.x (incomplete list), 5.x, No plugin needed
The Basic Antispam Plugin provides basic antispam features like: allow anonymous comments, detect feedback duplicates, feedback sensitivity to links, apply rel="nofollow", block spam referers, check referers for URL and check trackbacks for our URL.
This plugin allows you to add CAPTCHAs to your site in the form of simple questions requiring simple text answers.
For example the site would ask "What animal is Bugs Bunny?" and the user would need to type in "rabbit" or "a rabbit".