How to overwrite /modules/user/user.module text?
You can use hook_form_alter to change this text

function mymodule_form_alter(&amp;$form, &amp;$form_state, $form_id) {
  switch ($form_id) {
    case 'user_profile_form':
    case 'user_register_form':
      $form['account']['mail']['#description'] = t('My text');
      break;
   }
}