In number of developed countries, direct mail represents such a important amount of the total volume of mail that particular rate classes have been established. In the United States and UK, for instance, there are bulk mail rates that enable marketers to send mail at rates that are considerably lower than regular first-class rates. In order to meet the requirements for these rates, marketers must format and sort the mail in special ways - which reduces the handling (and consequently costs) required by the postal service.