Many mailers choose to presort their mail because it results in cheaper postage. Because you're doing some of the work, it costs the Postal Service less money to process and deliver those pieces of mail. We pass that savings on to you in the form of postage discounts. Basically, "presorting" means grouping your mail by ZIP Code. All of the pieces going to the same destination get grouped into the same bundle or tray. You’ll sort to specific areas, and then work your way up to more general areas. All leftover mailpieces are put together.

Some beginning mailers choose not to presort their mail; instead, they pay the full First-Class Mail rate, put stamps on their mailpieces, and drop them in a collection box. That's easy! Other mailers don't want to presort their mail but still want to get the lower postage rates. To do that, they use a presort bureau or letter shop[1] to prepare their mail.

The interactive decision tree[2] that will ask you some simple questions and guide you to instructions for sorting any class of mail.

An Introduction to Mailing for Businesses and Organizations (DMM 200)[3] – provides an overview of the discount mail process.