One of thousands of D.C. absentee ballot envelopes printed for the November election that failed to include a postage-required box. The U.S. Postal Service says it will still deliver absentee ballots without stamps, but the D.C. Board of Elections is urging people to include a Forever stamp to be safe. (D.C. Board of Elections)

An oversight by the D.C. Board of Elections meant more than 10,000 absentee ballot envelopes sent to voters did not include a reminder to include stamps, creating confusion two weeks before Election Day.

Those envelopes normally have an “additional postage required” box for stamps, but the language was not included on the sample envelope submitted to a printer earlier this fall, said board spokeswoman Rachel Coll.

Still, the U.S. Postal Service said it delivers absentee ballots with insufficient postage and charges the local elections agency instead.

“The Postal Service is steadfast in our commitment to support democracy,” spokeswoman Kim Frum said. “We will not deny a voter their right to vote by delaying a time-sensitive ballot because of insufficient postage.”

But several commenters on the local D.C. POPville blog, which first raised the stamp issue, said absentee ballots without postage had been returned to them.

Frum said she wasn’t aware of such cases. The Postal Service has been delivering unstamped absentee ballots to the D.C. Board of Elections, according to Coll.

If voters do have unstamped absentee ballots returned, they can mail them again with the correct postage — a single Forever stamp — or drop them off at the Board of Elections offices at 1015 Half St. SE or at their voting precinct on Election Day.

Elections officials warned that including unnecessary materials in their absentee ballot envelope, such as the voter guide or proof of identification, may require more stamps.

The agency cannot reprint new envelopes for future absentee ballot requests before Election Day, Coll said. The Board of Elections website leads with an image reminding people to affix a stamp to absentee ballots.

Council member Charles Allen (D-Ward 6), who leads a committee that oversees the Board of Elections, says the D.C. government should prepay absentee ballot envelopes in the future.

“I’ll look to fund it in the budget for future elections — no need to overthink this or leave in place a barrier to voting,” Allen said in a statement.

In Virginia, elections officials found that college students struggled to vote absentee because they didn’t know where to buy stamps, WTOP reported.

Have you had an unstamped absentee ballot returned to you? If so, please email fenit.nirappil@washpost.com.