A federal undercover investigation led to the arrests of numerous people who are accused of stealing mail.
Authorities said the suspects went digging through the large blue collection boxes at post offices, looking for checks, cash and anything else they could steal.
The crime is called "fishing" and the problem is growing in South Florida.
In some cases, the thieves use homemade contraptions to steal the mail. Authorities said one of the contraptions is a weight that is attached to rope with duct tape facing out.
Their hope is that the mail that is dropped in sticks to the tape.
Authorities said the scammers are out for people's financial information.
There has been 16 federal arrests related to fishing since October 2016 and another 16 arrests through the state attorney's office.
Post offices throughout South Florida are taking preventive measures.
In some locations prone to fishing, the blue collection boxes are being taken out.
The charges for those arrested for fishing range from identity theft to destruction of mail.