<prompt> Translate the following text to EnglishKwa madhumuni ya uchambuzi huu, barua ya muswada au malipo inafafanuliwa kwa ujumla kama barua ya darasa la kwanza inayotumiwa na kaya kulipa bili zao na barua ya darasa la kwanza inayotumiwa na wasio-nyumba kutuma bili kwa kaya.  <response>: For the purpose of this analysis, billpayment mail is broadly defined as First-Class Mail used by households to pay their bills as well as First-Class Mail used by non-households to send bills to households. 