For example, the United States Postal Service (USPS) defines bulk mail broadly as "quantities of mail prepared for mailing at reduced postage rates." The preparation includes presorting and placing into containers by ZIP code. The containers, along with a manifest, are taken to an area in a post office called a bulk-mail-entry unit. The presorting and the use of containers allow highly automated mail processing, both in bulk and piecewise, in processing facilities called bulk mail centers (BMCs).
In 2009, the USPS announced plans to streamline sorting and delivery, which would recast the BMCs as "Network Distribution Centers". Postal Service to Revamp Bulk Mail Center Network Parcel, February 25 2009 Changes In Store For Postal Bulk Mail Center Network PostalReporter News Blog, February 26 2009