EDMOND, Okla. (KFOR) – Some Oklahomans were out thousands of dollars after they said their mail was stolen from big blue mailboxes outside their post office. Edmond police confirmed to News 4 they have had reports of the problem in recent weeks, but the United States Postal Inspector was investigating.

Jamie Hilburn said she was a victim of the scam.

“I had a cashier’s check and a personal check in one envelope,” said Hilburn. “The cashier’s check got cashed. They attempted to cash the personal check, and that bank rejected it.”

Hilburn was out nearly $3,000.

Another Edmond woman told KFOR she slipped her $210 water bill into the outside collection box at the post office on Covell Road, near Kelly, this week. She said she checked her bank statement a few days later and found the check was cashed for $9,500.

One bank News 4 spoke with said scammers made off with $45,000 from one of its customers.

Another victim said an Edmond police officer told her he suspected thieves were using string and adhesive to lift the letters through mail slots, but that has not been confirmed. Once thieves get the mail, they use a process called “check washing.” That’s were they use chemicals to wash away ink, so the checks can be made out to someone else.

Postal Inspectors said they have recovered more than $1 billion in counterfeit checks every year. The best way to protect yourself was to never drop mail in an outside box after the last pick-up time on the blue box.

Jarrell Hollinsworth used the post office on Covell three to four times a week. He said he always goes inside because of this problem.

“I don’t have to worry about anybody breaking into nothing or anything like that,” said Hollinsworth.

U.S. Postal Inspectors have been monitoring the Edmond location on Covell, near Kelly. But several outside post office boxes have also been targeted in recent weeks.