This is “must have” WordPress anti-spam plugins. They’ll help you a lot. The one I like the most is the first one in the list.
Here we go:
Akismet – a very popular plugin which comes by default with WordPress. To use it, you need to signup for a WordPress acount and get an API key for your website.
2. Cookies for Comments
Cookies for Comments – Sets a cookie that must exist for a comment to be allowed.
WP-SpamFree – The WP-SpamFree plugin for WordPress seems to be much better than Akismet at blocking spam bots.
4. Spam Karma 2
Spam Karma 2 – This one assigns a karma score based on multiple factors like the age of the post, the email, if there’s a link inside, etc, etc.
5. Bad Behavior
Bad Behavior – though mainly used as a comment spam protection plugin has reliable security features too.
6. Math Comment Spam Protection Plugin
Well, I think this tools are enough to keep you away from spam comments. Test them and use the one(s) you like the most.