Comment moderation is a WordPress feature, which is specifically designed to let you manage comments on your website. With this feature, none of the comments will appear on your page without receiving your express approval.
While moderation is traditionally associated with addressing Comment Spam, it can also be applied more generally. Check the Fighting Comment Spam section if you wish to learn more about comment spam.
Before a comment is posted to your blog, it undergoes a bunch of tests run by WordPress. In case a comment fails to pass one of these tests, it will not be displayed immediately on your website. Instead, the comment will be moved to the moderation queue, which is the process of manual deletion or approval performed by the administrator of the blog.
You are free to specify which comments should be held for moderation simply by navigating to your Settings > Discussion subpanel page.
In case you want each comment to pass moderation before being shown on your website, check the following option: “An administrator must approve the comment”, which is located in the category “Before a comment appears”.
If you prefer to let harmless comments through, yet send suspicious ones to the queue for moderation, it is necessary to determine a set of rules for recognizing suspicious comments. These specifications can be made in the Settings →Discussion > Comment Moderation section.
There are several options that allow you to specify suspicious comments. First, a comment can be held for moderation if it contains an excessive number of hyperlinks. Usually, the majority of regular comments contain no more than two links, while having a large number of links is common for spam comments. Examine the comments on your website and and specify the value that will be appropriate for your audience.
Note: In WordPress version 1.5.2, and, quite likely, some others, if there is no number entered in the comment moderation links box (i.e. you left it completely blank), every anonymous comment (and, perhaps, others too) is automatically sent for moderation to the Manage Comments SubPanel, even if no restrictions are specified in the Discussion Options Subpanel.
The second way is to determine a set of moderation keys that will cause the comment to be held for moderation, in case detected anywhere in the comment. You can specify these keys one per line in the large text area, which is normally left blank by default. You can choose to include swear words, IP addresses, Spam words and Regular expressions to moderation keys.
When a new moderation key is added, we recommend you to test its validity through checking earlier comments. All you have to do is click the link named Check past comments against moderation list, which can be found under the text box that contains moderation keys. This way, WordPress will check previous comments in accordance with your recent set of keys, and inform you which of them will be marked for moderation.
As for the box entitled Comment Blacklist, it functions the exact same way the comment moderation box does, with the only exception that the comments that contain these words will be deleted at once, and with no notification. So we give you a heads up, as genuine comments can get deleted and you might not even know they were there in the first place.
A number of weblog programs address comment spam through “blacklisting”. This means that if you try to leave a comment with a domain or a word that is on the blacklist, then your comment automatically gets refused.
So why didn’t WordPress adopt this approach? The fact is, early in designing a way to deal with the issues that people kept having with comments, we promised we will do no harm.
Weblogs are all about communication, so anything that interferes with this process, is considered harmful to the medium. However, while blacklisting rejects the comments that contain a term in the moderation keys (which is our variant of the blacklist), we chose to simply hold it for the moderator to review. This way, if the filters caught a legitimate comment by mistake, the author of the weblog will still see it, and will be able to reply.
Surely, with this approach there may be a large number of comments on your site that you would want to get round the moderation queue. Thus, we did our best to help you manage a great number of comments as quickly and easily, as it is possible. For extra resources and information, check the articles dedicated to Fighting Comment Spam.