Thieves are riding around Bradley County roads looking for raised mailbox flags and rifling the stamped mail for cash and checks, the sheriff's office says.
Spokesman Adam Lewis said the office has received several complaints about stolen mail over the last couple of months.
He said it's a bad idea to mail checks from home, or cash at any time.
The safest way, Lewis said in a news release, is to drop envelopes in U.S. Postal Service mailboxes or take them to the post office.
The postal services Informed Delivery service is a free program that sends which notifies recipients by email to expect mail on any certain day. People can sign up at informeddelivery.usps.com.
Anyone who sees thieves stealing mail or suspicious vehicles in their neighborhood is asked to call the Bradley County Sheriff's Office Tip Line at 423-728-7336.