Official mail is mail sent from, or by, an authorized department of government, governmental agency or international organization[1] and normally has some indication that it is official; a certifying cachet, return address or other means of identity, indicating its user. In some countries, postage stamps have been issued specifically for official mail.
Official stamps were intended for the same purpose as regular postage stamps except that they were unavailable for purchase at post offices. While most stamps are denominated some have no value imprint.[1]