Coding  Accuracy Support System (CASS) Vendors

Direct  Mail (How to plan, execute and deliver a direct mail campaign.)

General  Information (USPS home page)

How To Read Postal Barcodes

National Postal Forum

Postal Explorer (Postage rates and fees, DMM information, customer support rulings, various publications.)

RIBBS(Up-to-date mailer information)

Track/Confirm   (Confirm delivery of Express Mail, Priority Mail/Parcel Post with Delivery  Confirmation/Priority Mail GlobalGuaranteed.)