In civicrm contact summary we see Contact ID / User ID, where User ID refers to the drupal. I will need to customize a token for this User Id which I am supposed to use in civimail. Here in this link https://wiki.civicrm.org/confluence/display/CRMDOC/Customized+%28and+Custom%29+Tokens ,drupal username can be fetched. But I need it for Drupal Id. Please suggest.