Stop-the-Clock is a category of USPS operation codes. The criteria for a Stop-the-Clock scan is that if a mailpiece passes through one of these Stop-the-Clock sort operations before 10:00 AM, it is according the USPS confirm program "nearly certain that it will be delivered by the carrier that same day". When a mailpiece receives this type of scan TrackMyMail will report the piece with an estimated in-home delivery day.
The Estimated In-Home projection is based on:
- The type of mail (letters vs. flats, standard vs. First-Class, etc.)
- The time and date of the scan by the postal service
- The type of scan
Based on those factors, we determine if the scan is a last scan (Stop-the-Clock) and we can estimate when the mailpiece will be in-home. IMB scans are assigned an operations code that relates to different levels of sort operations the postal service performs. This is where we see the Stop-the-Clock codes that the postal service recognizes as a code that indicates same-day delivery. The scans posted on our website are the most recent last scan or Stop-the-Clock scan. A Stop-the-Clock scan occurs for a mailpiece when it goes through any one of the sort operations that predict same-day delivery with a high level of certainty.
Our system uses an algorithm that incorporates all of the Stop-the-Clock operations codes, the time that the mailpiece was scanned, and the type and class of mail to determine an estimated in-home date which is then posted on the website. The initial scans for a mailpiece can be viewed by either downloading the USPS raw data or by using our Mail Piece History report which provides the first scan information.
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UPDATED: August 14, 2021