if @state.has_key?('email')
        invalid("config email recipients is missing or invalid") unless @state['email'].has_key?('recipients') && @state['email']['recipients'].is_a?(String) || @state['email']['recipients'].is_a?(Array)
        invalid("config email from is missing or invalid") unless @state['email'].has_key?('from') && @state['email']['from'].is_a?(String)
        @state['email']['from'] = interpolate_command(@state['email']['from'])