Simplest comment spam catcher

Adds a hidden field to comment forms, which will subsequently be auto-filled by spam-submitting robots. If the form
submission contains a value, the comment will not be saved, because only robots will see the field and fill it out.

Simple!

Any form which is processed using the hook comment_form_after_fields (building the form HTML) and preprocess_comment
(for processing the form submission) will be extended with this functionality.

This plugin doesn’t block or catch any form submissions which have been filled manually in a browser, so you may still
receive the occasional advertising or sales message as a post or page comment. However, blocking automatically-generated
spam messages will reduce the number of unwanted messages greatly.