All ballots must be turned in by 6 p.m. on Election Day, Tuesday, Nov. 5.
Officials say they don't believe it's a widespread issue.
For voting in Jefferson County, 16 additional locations will open 6 a.m. to 6 p.m. Tuesday along with the four that were open for early voting.
Special Agent Scott Balfour from the U.S. Postal Service Office of Inspector General says agents identified the postal employee responsible for discarding the mail.
Kentuckians still have a lot of opportunities to vote early.
A judge had cited slow mail delivery because of the coronavirus as a reason for extending the count if ballots were postmarked by Nov. 3.
In Jefferson County, 218,000 absentee ballots were requested and sent.
Dewey Clayton, political science professor at the University of Louisville, said the high turnout may speak to voters being more engaged.