Bulk mail

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.

[1][2] Although bulk mail, junk mail, and admail are, strictly speaking, not synonymous, the terms are used in common parlance to refer to unsolicited invitations delivered by mail (typically, but not invariably, at bulk rates) to homes and businesses.