Contact Us is not completely rewritten, but its file type is changed to .html. You can try something like this, but if it doesn't work then use Google to look for alternative answers:

Redirect 301 /contact_us.html http://www.otherdomain.com/other_contact_us_page

It may have been better just to install reCaptcha on the Contact Us page, or else change its content so that it just gives people the bricks-n-mortar address, phone number and the email address (minus the actual contact form).

Vger