Cannot get Model Validation working for email field

In Controller i have:

$email = $this->request->getPost('email');

            $obj = new Users();
            $valid = $obj->validation($email);

if(!$valid)
        {
            $this->flashSession->error("invalid email!");
        }
         else
         {
            $this->flashSession->success("good email!");
         }

In Model:

public function validation($email) { $this->validate( new Email( array( 'field' => 'email', 'required' => true, ) ) );

    if ($this->validationHasFailed() == true) {
        return false;
    }
}

Validation always returns error message. Please advise, what i am lacking!