Enable the 'access user contact forms' for registered users by default.
function contact_update_7002() {
// Do not use user_role_grant_permission() since it relies on
// hook_permission(), which will not run for contact module if it is
// disabled.
db_merge('role_permission')
->key(array(
'rid' => DRUPAL_AUTHENTICATED_RID,
'permission' => 'access user contact forms',
'module' => 'contact',
))
->execute();
}