Overwhelmed with spam?
If your site is actively being spammed, check out WordPress tip #4 right now: how to eliminate automated comment spam.
Once you’ve stopped the comment spam, you’ll likely find yourself with dozens, if not thousands of pending comments. Since WordPress only lets you mark 20 comments as spam at a time, it would take an unreasonable amount of time to delete them all.
The solution: Delete Pending Comments Plugin.
With the Delete Pending Comments plugin, you can completely remove all pending comments without affecting any of the real, published comments.
To use it, install & activate the plugin, then visit the new Delete Pending Comments menu found under Comments.
The plugin makes you type in the phrase, “I am sure I want to delete all pending comments and realize this can’t be undone”, to make sure you understand the implications. Then, simply click the Delete Pending Comments button, and they’ll be removed from your site immediately.
It’s not a bad idea to backup your site before using this plugin, just to be safe.