A bank may elect to process a deposited check without an endorsement, especially when the deposit occurs through an automated teller machine, but that's not always the case. Indeed, many banks have policies of reversing check deposits without endorsements. It also is in your best interest to endorse checks before deposit to restrict the ability of someone else to deposit or cash the check.
Check Endorsement Basics
Banks typically require you to endorse the back of a check before deposit. To restrict unauthorized access, write "For Deposit Only" on the endorsement section along with your signature. This endorsement means only you, the payee, can deposit the check into your account. Someone who is not the designated payee would then be unable to deposit or cash the check.
Many banks accept endorsed check deposits through their Smartphone applications. This process involves scanning images of the front and back sides of the check and submitting them to the bank. Banks normally require and advise customers to endorse the back of the check before taking and submitting photos. This endorsement ensures that the customer using the app and signing into the account is the proper payee on the check. Deposits may not get credited to your account without endorsements.