A new U.S. Postal Service rule clarifying what a postmark actually represents is triggering backlash online, with critics warning the policy could create confusion and jeopardize time-sensitive mail — including election ballots, tax filings, and bill payments.

Postmarks, which include a USPS date stamp, are often used as proof that a piece of mail was submitted by a legal deadline. But the new rule, which took effect last week, clarifies that a postmark does not "necessarily" reflect the date the USPS "first accepted possession" of the piece of mail.

That distinction is now drawing sharp reaction on social media, with some users blasting the change as unfair and calling for immediate reform.

"The post mark rule change is utter BS," Peggy wrote in a post on X.

"You need machines that electronically add a postmark as soon as letter is put in the box. Even if those machines are only inside the post office," the user continued.

"Too many events depend on the postmark date. Whoever came up with this idea should be FIRED!!!!"

Another predicted that the postmark rule change would have negative repercussions for customers who depend on the USPS to deliver important documents.   

"So the @USPS changed the postmark rules and it truly isn't getting enough attention," Eh-tan-lee wrote in a post on X.

"If you're voting by mail, sending payments, filing deadlines, etc. then they are setting you up for failure."

Still, not everyone was upset over the agency's clarification.

"Literally nothing is changing...it's always been like this, you don't get a postmark when you drop it in a blue box or if you drop it off in a slot at the post office...it gets post marked when it gets processed," Andrew1776 wrote in a post on X.

"If you want it post marked just go to the counter and ask for it. It's been like this for a long time, at least as far back as I can remember."

The USPS says it has not changed its postmarking practices but issued the rule to make clear to the public what a postmark denotes.

The agency notes that most postmarks are applied at regional mail-processing hubs rather than at the local post office where a customer drops off a letter or ballot.

The clarification comes as the Postal Service undertakes a major overhaul that includes eliminating multiple daily trips between post office locations and regional processing facilities.

As a result, some Americans — particularly in rural areas far from processing hubs — may experience delays between dropping off mail and having it postmarked.

The timing is drawing heightened scrutiny because many states rely on postmarks for counting mailed ballots.

Voting by mail expanded during the pandemic and made up about 30% of turnout in the 2024 election, according to federal data, down from a high of about 43% in 2020.

The National Conference of State Legislatures says 14 states — including battleground Nevada — accept ballots that arrive after Election Day, as long as they are postmarked on or before Election Day.

The USPS changes also come as President Donald Trump continues pushing to curb mail-in voting.

Trump has criticized the practice as rife with fraud and signed an executive order in March to mandate changes to mail-in balloting and other election practices. It has been blocked in part by the courts.

Meanwhile, four states — Kansas, North Dakota, Ohio, and Utah — eliminated their grace periods in 2025 for counting ballots received after Election Day.

The dispute over late-arriving ballots is now headed to the U.S. Supreme Court, which will decide whether states may count mail-in ballots that arrive after Election Day.

In a statement obtained by CNN, the USPS said customers who want to ensure a piece of mail receives a postmark can take it to a post office retail counter and request a manual postmark.

Customers also have the option of using certified or registered mail for a fee.