<prompt> Translate the following text to EnglishKatika kutoa huduma na katika kuanzisha uainishaji, viwango, na ada chini ya kichwa hiki, Huduma ya Posta haipaswi, isipokuwa kama imeidhinishwa maalum katika kichwa hiki, kufanya ubaguzi wowote usiofaa au usiofaa kati ya watumiaji wa barua, wala haipaswi kutoa upendeleo wowote usiofaa au usiofaa kwa mtumiaji yeyote.  <response>: In providing services and in establishing classifications, rates, and fees under this title, the Postal Service shall not, except as specifically authorized in this title, make any undue or unreasonable discrimination among users of the mails, nor shall it grant any undue or unreasonable preferences to any such user. 