rafsal

Thank you, it’s work on WP v3.5.1 !

Ok, now will try

This plugin hasn’t been updated in over 2 years. It may no longer be maintained or supported and may have compatibility issues when used with more recent versions of WordPress.
Requires: 2.9.2 or higher
Compatible up to: 3.0.5
Last Updated: 2010-3-31

Hashcash for Contact Form 7 requires the WP Hashcash plugin to be installed and activated. Please install the WP Hashcash plugin

Yes, I did