[Plugin: Contact Form 7] Silent Spam Trap

Maybe this topic went out of date but it is easy to solve with the quiz fields. Creating a quiz field with an empty answer can do that.

For example, an quiz like

"Please leave this field empty (spam defense)|"

wont validate if anything is typed into that field. (Note there is nothing between the pipe and the closing quotes.)

You can push this field aside with css

postion : abolute; top : -999em; left : -999em;

to prevent your users from misunderstanding the field.