The US Postal Service has published new rules for shortpaid and unpaid Information-Based Indicia (IBI) and Express Mail:
Express Mail Shortpaid Procedure
For an Express Mail Next Day, Second Day, Military, or Custom Designed Service item received at the origin office of mailing with insufficient postage, the mailer is contacted to correct the postage deficiency prior to dispatch of the Express Mail item. If the mailer cannot be contacted before dispatch from the origin office, or if the Express Mail item with insufficient postage is identified during processing operations or at the destination Post Office, the Express Mail item is endorsed “Postage Due”, marked to show the total deficiency of postage and fees, and then dispatched to the destination Post Office for delivery to the addressee upon payment of the deficiency.
If the addressee refuses to pay the postage due amount, the Express Mail item is endorsed “Return to Sender–Refused.” The postage deficiency is then collected when the Express Mail item is returned to the original sender. If the original sender chooses to remail the item, a new Express Mail label and new postage and fees must be affixed.
Postage Evidencing Systems
Postage meters, PC Postage products, and Click-N-Ship are collectively identified as “postage evidencing systems.” A postage evidencing system is a device or system of components a customer uses to print evidence that postage required for mailing has been paid.
Information-Based Indicia (IBI) are digitally generated indicia that include a two-dimensional barcode.
Revenue deficiency includes both shortpaid and unpaid postage which
occurs when any mailpiece has less postage than required for the
applicable price category and associated class, weight, shape, zone,
and extra services.
Shortpaid postage is revenue deficiency for which the valid postage
on a mailpiece is less than the amount due.
Unpaid postage is a revenue deficiency for which postage is deficient due to the lack of affixed postage or the use of counterfeited, replicated, duplicated, falsified, or otherwise modified postage.
Detection Process for Revenue Deficiency
When potential shortpaid or unpaid IBI postage is detected on a
mailpiece, the Postal Service will subsequently verify the postage to
ensure its validity and determine whether the amount is sufficient.
When the IBI postage on a mailpiece is confirmed to be shortpaid or
unpaid, the corrective measures outlined below will be taken to recover
the applicable revenue deficiency.
Electronic Notification of Revenue Deficiencies
In most cases, the Postal Service will electronically notify both
the mailer and the postage evidencing system service provider of the
revenue deficiency and deliver the mailpiece to the addressee. The
electronic notification provides a link to the USPS[reg] Web-based
customer payment portal that will enable the mailer to pay or dispute
the revenue deficiency. In the event that electronic means are
unavailable, other existing processes may be used to recover revenue
deficiencies as required.
Full text of the Federal Register notice, including the dispute resolution process: Federal Register, Volume 76 Issue 129 (Wednesday, July 6, 2011).