Comment spam is a reality that all bloggers know. If you allow for comments on your site, then spammers will look to spam and create backlinks. Using WordPress, you have robust built-in tools to prevent comment spam, and there is a broad range of comment spam protection and defense plugins for additional coverage and protection.
|Akismet||Akismet checks your comments against the Akismet Web service to see if they look like spam or not.||4.8||1M||Link|
|SI CAPTCHA Anti-Spam||Adds CAPTCHA anti-spam methods to WordPress on the forms for comments, registration, lost password, login, or all. For WP, WPMU, and BuddyPress.||4.2||300K||Link|
|Antispam Bee||Another popular solution to fight spam is Anti-spam Bee.||4.7||200K||Link|
|WP-SpamFree Anti-Spam||Powerful anti-spam plugin that eliminates blog comment spam. Finally, you can enjoy a spam-free WordPress blog! Includes contact form.||4.0||60K||Link|
|WP-SpamShield Anti-Spam||An exceptionally powerful WordPress anti-spam plugin that eliminates comment spam, trackback spam, contact form spam & registration spam.||4.9||100K||Link|