10 Ways to Block Comment Spam on Your Blog

Comment spam is a common issue for website owners and bloggers. It involves irrelevant or inappropriate comments posted on your site to gain backlinks or promote products. 

Not only does comment spam make your site look unprofessional, but it can also harm your SEO and lessen your chances of being seen as an authority site. Let’s explore 10 strategies to tackle comment spam effectively.

In this article:

1. Use Anti-Spam Plugins
2. Enable Comment Moderation
3. Implement CAPTCHA
4. Use the Honeypot Technique
5. Disable Commenting on Old Posts
6. Use Blacklists and Whitelists
7. Limit Links in Comments
8. Require User Registration
9. Use Third-Party Commenting Systems
10. Monitor and Analyze Comments Regularly

1. Use Anti-Spam Plugins

Anti-spam plugins can automatically detect and block spam comments. They use various algorithms to differentiate between genuine and spammy comments.

Anti-Spam Tools to Use

• Akismet: One of the most popular anti-spam plugins, Akismet filters out spam comments and trackbacks.
• Spam Prevention by CleanTalk: This tool uses cloud-based algorithms to stop spam without CAPTCHA.
• Antispam Bee: This plugin is effective and respects user privacy by not storing data on external servers.

These plugins scan comments for known spammy patterns, suspicious URLs, and other indicators. They can filter out comments automatically or mark them for your review.

There are also specific tools for tackling specific types of comment spam. For instance, Stephen Ford of Media Fortress used Norton, Pentest Tools, and Sucuri to combat k.html web spam. He talks more about k.html spam links and what you can do about them in his LinkedIn post.

2. Enable Comment Moderation

Comment moderation requires you to approve each comment before it appears on your site. This gives you control over what gets published.

How to Implement Comment Moderation

1. Go to your website’s admin panel.
2. Navigate to the settings or discussion section.
3. Enable the option for manual approval of all comments.

Manual moderation allows you to filter out spam manually and ensure that only relevant comments are posted. However, Jon Morgan, CEO and Editor-in-Chief of Venture Smarter, notes that manual moderation isn’t sustainable, especially if you’re getting attacked by up to hundreds of comments per day.

The spammers were relentless, and their comments kept coming back, clogging up our system. That’s when we decided to install a plugin that utilizes CAPTCHA technology to filter out automated comments.

Jon Morgan, Venture Smarter CEO and Editor-in-Chief

3. Implement CAPTCHA

CAPTCHA (Completely Automated Public Turing test to tell Computers and Humans Apart) helps distinguish between human users and bots.

Types of CAPTCHA

• reCAPTCHA: Developed by Google, one of the most widely used and effective CAPTCHA systems; automatically verifies users without requiring any interaction unless deemed suspicious.
• hCAPTCHA: An alternative that is also user-friendly and secure; offers strong privacy protections.
• Simple Math CAPTCHA: Asks users to solve a basic math problem to prove they are human; simple and quick for users to complete.

CAPTCHA requires users to complete a simple task that is easy for humans but difficult for bots. This reduces the number of automated spam comments.

4. Use the Honeypot Technique

Rongzhong Li, founder of Petoi, a programmable bionic robot pet shop, admits that they’ve also experienced comment spam attacks, mostly through automated bots. Another solution is the honeypot technique, which involves adding hidden fields to your comment forms that are invisible to human users but visible to bots. 

The premise is that since human users cannot see or fill out the hidden field, any submission with data in this field is likely from a bot and can be rejected.

How to Implement the Honeypot Technique

1. Add a hidden field to your comment form using CSS to hide it.
2. Set up your server to reject any submissions that include data in this hidden field.

This technique effectively deters bots without inconveniencing human users. It also works well in combination with other anti-spam measures.

5. Disable Commenting on Old Posts

Old posts often become targets for spam comments. Disabling comments on these posts can reduce SEO spam.

How to Disable Comments on Old Posts

1. Go to your website’s settings.
2. Set a limit for how long after posting comments can be made (e.g., 30 days).
3. Save the settings.

This reduces the risk of spam on older posts while keeping the discussion open on newer, relevant content.

6. Use Blacklists and Whitelists

Blacklists block specific email addresses, IP addresses, or keywords from posting comments. Whitelists allow only approved users from legitimate root domains to comment.

How to Implement Blacklists and Whitelists

1. Access the blacklist/whitelist settings in your comment moderation system.
2. Add known spammy email addresses, IPs, or keywords to the blacklist.
3. Add trusted users to the whitelist.

This proactive approach can prevent known spammers from posting comments and ensure that only genuine users can comment.

7. Limit Links in Comments

Spammers often post comments with multiple links. Limiting the number of links allowed in a comment can reduce spam. You can set a limit to the number of links allowed in each comment through your site’s comment settings. This discourages spammers from link schemes who want to post multiple links and helps keep your comment section clean.

8. Require User Registration

Requiring users to register or sign in before commenting adds an extra step that can deter spammers. Gal Cohen, field area manager at JDM Sliding Doors, also found that restricting comment privileges to registered users lowers spam.

Check your site settings, and require login for posting comments. This will prevent spammers from entering your site while encouraging genuine users to engage more deeply with it.

9. Use Third-Party Commenting Systems

Third-party commenting systems like Disqus and Facebook Comments provide built-in spam protection and additional moderation features.

Popular Third-Party Commenting Systems

• Disqus: Offers extensive moderation tools and spam filtering.
• Facebook Comments: Uses Facebook’s spam detection and user authentication.
• IntenseDebate: Provides spam protection and user moderation features.

These systems often have more advanced spam detection and moderation features than default commenting systems. They also require users to have accounts, which can reduce spam.

10. Monitor and Analyze Comments Regularly

Regular monitoring and analysis of comments can help you quickly identify and remove spam. Set aside time daily or weekly to review new comments. Additionally, use your website’s analytics tools to track comment activity and identify patterns. Regular monitoring helps maintain a clean comment section and allows you to spot new spam tactics quickly.

Keep Comment Spam Away

Tackling comment spam is essential for maintaining a professional and engaging website. By using a combination of these strategies—such as anti-spam plugins, comment moderation, CAPTCHA, and honeypot techniques—you can significantly reduce spam and improve your site’s SEO. Implement these best practices today to keep your comment sections clean and user-friendly.

Tackling comment spam is just one piece of the puzzle. To truly boost your site’s performance, pair your anti-spam efforts with a robust link-building strategy.

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