USPS Postmark Update: What It Means For Proof Of Shipping For Online Sellers

A recent USPS postmark update won’t impact how marketplaces like eBay and Amazon measure seller performance, but it could change what sellers can point to when shipping timelines are questioned or disputes are filed.

Online platforms rely on carrier scans and internal tracking data to evaluate shipping performance, so postmark dates are largely irrelevant for most sellers. But for those using untracked or low-cost mail services, this shift could weaken a long-standing backup form of proof that helped resolve buyer disputes and explain delivery delays when scans were missing or late.

What changed?

As of December 24, 2025, USPS has officially clarified how postmark dates work, providing explicit definitions of what a postmark really means - and what it doesn’t.

The Postal Service now openly says a machine‑applied postmark shows the date a piece first hits automated processing, not necessarily the day a customer dropped it in a box, handed it to a carrier, or left it at the counter.

In a statement laying out some myths and truths about postmarks related to this recent announcement, USPS says:

• “The Postal Service has not changed and is not changing our postmarking practices… Postmarks are generally applied by machines at our originating processing facilities and will continue to be applied at those facilities in the same manner and to the same extent as before.”​
• “Postmarks applied at those facilities will continue to contain the name or location of the facility that applied the postmark and the date on which the first automated processing operation was performed on that mailpiece.”​
• “This means that the date on the postmarks applied at our processing facilities will not necessarily match the date on which the customer’s mailpiece was collected by a letter carrier or dropped off at a retail location.”​
• “Postmarking is not and has not been a service that the Postal Service has provided to the public [to prove when mail was sent]. The postmark has always fundamentally existed to perform functions internal to Postal Service operations.”​
• Customers who want proof of when USPS first accepted a piece “may purchase a Certificate of Mailing. Registered Mail and Certified Mail services also provide mailing receipts for individual mailpieces

What does this mean for online sellers?

Honestly, there will likely be very little impact for the vast majority of online sellers with this update since most marketplaces like eBay, Amazon, Etsy and more specifically use carrier scans and tracking data to evaluate on-time shipping and delivery performance.

Currently, if you drop a marketplace shipment in a USPS box or bin, it may not get an acceptance scan until the next day or even later - and that's not changing and has nothing to do with postmarks.

This clarification from the post office simply just confirms more explicitly how things were already working, it doesn't really introduce anything significantly new or different to the process.

However, sellers may still experience some impact when tracking is missing or late since USPS is now on record that a machine‑applied postmark shows the date of first automated processing, not the day you dropped the mail off, which undercuts using postmarks as proof you shipped on time if questioned by buyers or as additional backup information provided for disputes.

For sellers who rely on untracked or lightly tracked services, the postmark used to be a convenient way to show, “USPS had this by X date”; now USPS explicitly says that date may be a day or more after collection, weakening that argument.

To be clear, many marketplaces likely wouldn't have previously accepted postmark date as proof of shipping any way, but it may have helped avoid having an issue escalated to a formal dispute when used in communication with buyers.

This makes getting counter acceptance scans or using SCAN forms, scheduled pickups that get scanned, or in‑person manual postmarks even more critical for sellers who routinely operate near tight handling‑time promises.

What does this mean for eBay Standard Envelope?

eBay Standard Envelope (ESE)was launched in 2021 as an affordable way for sellers to ship small, inexpensive items like trading cards, stickers, patches, postcards and stamps.

ESE is considered metered machinable letter mail and does not get traditional USPS package tracking or counter acceptance scans.

These shipments rely on automated sort scans reading the special barcode on the envelope and eBay’s internal tracking, not the printed postmark date as legal proof of mailing - so in practical terms, the new USPS postmark rule should not materially change how eBay Standard Envelope (ESE) works.

For eBay metrics and seller protections tied to ESE, nothing in the USPS postmark clarification changes the underlying scan behavior: if the automation reads the barcode, eBay gets data; if it does not, there is still no external USPS tracking to fall back on.

So just like with other shipments, this USPS postmark update likely will not directly impact how eBay determines metrics or seller protections for ESE, but indirectly it may make it more difficult to try to use the postmark date as backup proof for any questions or disputes that may arise.

Bottom Line

The recent USPS postmark update is likely to have very little impact on most online sellers - carrier scans and tracking will still be used by marketplaces to evaluate seller shipping performance and determine on-time shipping and delivery metrics.