Here are 4 things you can do:

  1. Install a captcha plug-in: This plug-in requires the user to perform an action to prove they are not robots. This could be typing in a word or number, solving a math problem, or–my personal favorite– simply checking a box.  Checking the box is my favorite because I’ve learned that the less a visitor has to do, the more likely they will be to complete the task.
  2. Use a spam filter: This is similar to captcha but does not require any front-end work.  The program works in a similar way to your email spam folder, filtering all messages, comments, registrations, and signups to determine whether they are spam. Most spam filters will send you a report of activity, just in case they filtered out something that shouldn’t have been.
  3. Disable unneeded comments boxes: This is pretty straight-forward. If you do not need comments, disable them.  The fewer avenues robots have to attack the better.
  4. Don’t neglect sign up & registration forms: Many people protect the contact form and the comments but forget about registration and sign up forms. Protect these with Captchas, too.