Merge/Purge
Duplication Elimination
Reformat Fields/Address Standardization
Delivery Point Verification (DPV)
Undeliverable-as-Addressed (UAA)
Postal Presorting
Coding Accuracy Support System (CASS)
National Change of Address (NCOA)
Ancillary Service Endorsements (ASE)

First, it is sorted according to the regional destination. After being delivered to the regional center, it is sorted again to determine the local Postal Office. Then it is sorted again to determine the carrier. Presorting your mailing list enables you to take advantage of postal discounts.