Use below code in your functions.php to Send Mail to sender also using Contact Form 7

add_filter( ‘wpcf7_additional_mail’, ‘my_wpcf7_use_mail_2_or_not’, 10, 2 );

function my_wpcf7_use_mail_2_or_not( $additional_mail, $cf ) {
    if ( “Send me a copy of this message” != $cf->posted_data[‘send_c’][0] )
        //$additional_mail = array();
        return $additional_mail;

}