The U.S. Postal Service is rolling out changes for postmarks in the new year — clarifying the new rules saying postmarks will be added when an envelope is processed rather than the day that it gets submitted. Whit Johnson reports. | ABC World News Tonight with David Muir

USPS Address Verification API

USPS Address Verification Service API

Address Verification Software

USPS issues guidance, info ahead of holiday shipping season

USPS issues nationwide warning: What to do if a mysterious package arrives on your doorstep