1. AkismetAkismet is a spam filtering service which protects your blog from comment spam submitted through comment form, trackback spam or pingback spam. When a new comment, trackback, or pingback comes to your blog it is submitted to the Akismet web service which runs hundreds of tests on the comment and returns true or false. You do not need to maintain any blacklist in your part. It saves the spams in the database for 15 days in case you want to check it out manually and then automatically deletes them.
The missing part is that you do not have control over your comments. You get a blackbox with no direct control over its actions. You have to rely on Akismet’s decision. However you can submit a comment as genuine comment which is marked as spam by Akismet to the Akismet service so that it learns from your submission. Many bloggers have complained of commenters being wrongfully flagged as spammers and vice verse. What if the Akismet web service is down? All your comments will simply go into the moderation queue.
2. Comment Guard ProSpams are of different kinds. Most of the users often complaint that even after using a popular spam protection plugin, the purpose is not being served. The reason for that is, your plugin might not have that code snippet to deny one particular category of spammers. Suppose you have WP spam free plugin, so you can never get rid of human submitted spams from that. That is where you will need an almost all-in-one spam protection plugin for yourself.
Comment Guard Pro (for WordPress) is designed to unobtrusively protect your blog against all types of comment spams – trackback spam, pingback spam, robotic spam using comment form, human submitted spam (where the spammers actually goes to your site to spam you; they are the hardest to detect), referrer spam etc. It provides multiple layers of protection against all kind of comment spams.
Comment guard pro plugins eliminates false positives (marks legitimate comments as spam) and false positive (marks genuine comments as spam). It is hard to eliminate false positives for large spam queue size say 2000-10000 manually. It might be ok for 5-10 comments in spam queue.
A big achievement with this plugin is, you have full control over your comments. It comes with fully documented open pluglet API and examples to enable you to write your own pluglets. Comment Guard Pro also includes Akismet as one of its spam filtering service.So if you are concerned about comment spamming in your blog, then this is perhaps the most comprehensive anti-spam plugin for your WordPress.
3. Simple Spam Filter PluginSimple Spam Filter looks for a particular pattern to distinguish a spam from a real commenter, like most of the other Spam filters. The best part for this plugin is, it can work along with Akismet and will display a captcha if Akismet flags a comment as spam. So the problem with Akismet (that it flags legitimate comments as spams sometimes) can be countered with it.
If a comment gets rejected, then an error screen will be shown with an explanation of why the comment was rejected. An optional captcha can also be configured to display, which allows people to confirm that their comment is indeed legitimate.
4. Bad BehaviorBad Behavior, though mainly used as a comment spam protection plugin has reliable security features too.
It prevents link spams and blocks the robots which delivers it. By acting as a gatekeeper, it prevents spammers from delivering their junk, and in many cases, from even reading your site in the first place. This helps your site’s load down, makes your site logs cleaner, and also contributes to prevent denial of service conditions caused by spammers.
Instead of merely looking at the content of potential spam, Bad Behavior analyzes the delivery method as well as the software the spammer is using. It is designed to work alongside existing spam prevention services to increase their effectiveness and efficiency. This is one of the most often upgraded WordPress plugin. You can use it.
5. WP-SpamFreeAs I have already said, Akismet was a good fighter but never a reliable one against these spams. God knows how many times I have seen Akismet predicting wrong spammers where I had deleted legitimate comments. Here is Wp-SpamFree that claims to eliminate bots but not humans.
Features (according to the makers)
Virtually eliminates automated comment spam from bots. It ensures that your commenters are in fact, human.
A counter on your dashboard to keep track of all the spam it’s blocking. The numbers will show how effective this plugin is.
No CAPTCHA’s, challenge questions or other inconvenience to site visitors – it just works.
No false positives, which leads to fewer frustrated readers, and less work for you.
You won’t have to waste valuable time sifting through your Akismet queue anymore, because there won’t be much there.
Now with Trackback and Pingback spam protection. and etc
7. Spam Karma 2.3Spam Karma 2 (SK2) is an anti-spam plugin for the WordPress blogging platform. It is meant to stop all forms of automated Blog spam effortlessly, while remaining as unobtrusive as possible to regular commenters
There is a Trackback referrer check and also a captcha backup . There are plenty of tabs with lots of options for general as well as advanced settings in Spam Karma 2.3.
8. Secure Form Mailer PluginThis plugin creates custom contact form for your blog and secures it from spamming. It has a wide range of features.
- Support for multiple instances
- An easy to use dynamic form generation system (any number of fields, in any order)
- Multiple recipients
- Multiple file attachments
- Optional auto reply feature
- An image verification system
- Numerous security features (including protection against email header injection)
- A message template system and etc.