They're not just altering checks taken from the blue boxes, police said they're also using victims' identities to access and steal money from their bank accounts.
Last holiday season the United States Postal service said it shipped 12 billion pieces of mail, and they are preparing for an even busier mailing season this year.
USPS said the new option is "simple, reliable and more affordable."
The latest robbery involving a local postal worked occurred on Dec. 29.
Mailboxes are being targeted too. It has some concerned about the safety of their mail.
Police said one of the men had a special key used to open public collection boxes.
If approved, a First Class Mail stamp would increase by 2 cents to cost 60 cents instead of 58 cents.
The tool provides people with a very anonymous way to send in crime tips.
The US Postal Service has temporarily removed some mailboxes in several major cities across the country, a security measure ahead of next week's inauguration of President-elect Joe Biden.
Nearly every state, including Indiana, received a letter from the USPS warning that it cannot guarantee all ballots cast by mail for the Nov. 3 election will arrive in time to be counted, even if ballots are mailed by state deadlines.