The most common benefit mailers find in using DSF2 processing is to append the walk sequence number required to take advantage of high density and saturation discounts.  DSF2 is a USPS® approved source for this information. DSF2 processing is available through USPS DSF2 licensees and a DSF2 Agreement must be completed prior to processing.

The DSF2 file contains over 165 million U.S. delivery points. In addition to the standardized address, attributes such as the type of delivery address (business, residential, seasonal) and the type of mail receptacle (curbside mailbox, mail slot in door, cluster box etc.) are on the file. It also identifies addresses with PO Box™ only delivery.

Here is how it works.

Your file is first run through CASS Certified™ ZIP + 4® software to standardize the addresses and append current postal codes. It’s then matched to the DSF2 database to append the walk sequence number and other address attributes. Name information is not used in DSF2 processing. Addresses that do not match a valid delivery point in the DSF2 file will be returned with footnotes identifying possible address errors.

Carrier route postal discounts are available for mail files that meet the density requirements and are sorted in either eLOT® or Walk Sequence. Line of Travel (LOT) numbers and sort flag are available through CASS Certified ZIP + 4 processing. Walk Sequence numbers are available through DSF2 processing. Presort software uses the Walk Sequence number to sort the mail file in the same sequence that the mail carrier will deliver the mail. This saves time for the USPS® mail carrier by eliminating the need to sequence mail prior to delivery and the mailer receives a lower postage rate.

The carrier route density requirements for discounts are as follows:

  • Basic enhanced carrier route must be part of a group of 10 or more to one carrier route.
  • High density enhanced carrier route requires 125 or more mail pieces per carrier route unless there are less than 125 delivery points within that carrier route, in which case a mail piece must be sent to each delivery point within the carrier route.
  • High density plus enhanced carrier route requires a minimum of 300 pieces per carrier route.
  • Saturation enhanced carrier route requires the mail pieces be addressed to 90% or more of the active residential addresses or 75% or more of the active possible delivery addresses (whichever is less) on each carrier route (100% if simplified address).

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