Announcement: 

USPS postmarks are now applied during processing rather than at drop-off, which means the date on a postmark may not reflect when mail was sent—creating challenges for businesses that rely on mailing deadlines and compliance requirements.

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A USPS postmark no longer reliably indicates when your mail was sent, and this shift introduces new risk for deadline-driven businesses. 

For decades, “postmarked by” carried a clear and trusted meaning. If something was mailed on Monday, the postmark showed Monday. That expectation can no longer be relied upon. 

Today, United States Postal Service (USPS) postmarks often reflect when mail is processed rather than when it is dropped off.

In a statement addressing postmarking practices, USPS explains:  “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 contain … the date on which the first automated processing operation was performed on that mailpiece.” 

For businesses that depend on mailing deadlines, compliance requirements, or documentation, this creates a real and measurable operational risk. 

What a USPS Postmark Used to Represent 

Historically, a postmark acted as informal proof of a mailing date. Courts, tax agencies, and businesses relied on it to confirm something was sent on time. 

Drop a letter in the mail, and that date appeared on the envelope. Entire workflows and compliance systems were built around that expectation. 

For years, the process felt predictable and dependable until now. 

How USPS Postmarks Work Today 

Although the postmarking practices haven’t officially changed, according to USPS, adjustments have been made to the transportation operations, which can result in “some mail pieces not arriving at our originating processing facilities on the same day that they are mailed. This means that the date on the postmarks applied at the 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.”  

This means the date printed on mail is no longer fully within the sender’s control. 

Why This Change Can Matter for Businesses 

Postmarks are still used to determine whether something was sent on time. 

This can affect:

• Tax filings, appeals, and refund requests
• Legal notices and compliance letters
• Business invoices, contracts, and other deadline-driven mail
• Any communication governed by “postmarked by” rules

Even a one-day difference can result in rejected filings, disputes, or penalties. This is a real operational risk, not a hypothetical one. 

The Hidden Risk of USPS Postmarks for Businesses 

This is what makes the change especially challenging. Even when mail is prepared correctly, postage is applied properly, and USPS guidelines are followed; the postmark date can still be determined by processing delays. 

Those delays are invisible to the sender. For organizations managing recurring or high-volume mail, assumptions that worked for decades are no longer enough. 

Businesses now need greater awareness of how mailing timelines are documented and interpreted. 

When a Postmark No Longer Tells the Full Story 

Consider a homeowners’ association that sends annual notices or policy updates. These mailings may not require Certified Mail, but the association still needs to demonstrate that notices were sent if a homeowner later disputes receiving one. 

The board prepares the mailing on time and drops it in the mail before the deadline. Later, the envelope shows a postmark dated after that deadline. Nothing went wrong operationally, yet the documentation no longer reflects when the mail was actually sent. 

This same risk applies across industries. Legal offices, healthcare administrators, property managers, financial teams, and corporate departments all send time-sensitive mail that does not require signatures but still demands accountability.  

When postmarks reflect processing time rather than send date, any organization relying on mailing deadlines can find itself without reliable documentation. 

What This Can Mean for Mail Going Forward 

Postmarks still exist, but they no longer provide the clear proof many businesses have relied on in the past. 

As USPS processing increasingly determines when postmarks are applied, organizations must rethink how they plan and manage deadline-sensitive mail. Sending mail earlier than stated deadlines is no longer optional—it is a practical step to reduce risk and account for processing delays outside the sender’s control. 

Businesses that build additional time into their mailing schedules gain predictability and confidence. Those who continue to rely solely on postmark dates may find themselves facing disputes or explaining delays they cannot document or prevent. 

Understanding what a USPS postmark represents today—and planning accordingly—is now essential for meeting deadlines and protecting business operations. 

To learn more about LetterStream, click here. 
 

Sources & References 

USPS — What Is a Postmark? 
https://faq.usps.com/s/article/What-is-a-Postmark 

USPS — Postmarking Myths and Facts 
https://about.usps.com/newsroom/statements/010226-postmarking-myths-and-facts.htm 

USPS Domestic Mail Manual (DMM) 604 — Postmarking Standards 
https://pe.usps.com/text/dmm300/604.htm 

U.S. Government Accountability Office — USPS Mail Processing Network Changes 
https://www.gao.gov/products/gao-24-106946 

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