The postal service received a text message reminding it of its arrears.

The reasons for receiving SMS messages without bank cards are as follows:

1. Error message: Sometimes the banking system or a third party institution may send the wrong short message, which may be caused by input errors, system failures and other reasons.

2. Fraudulent information: Sometimes, criminals will send fraudulent short messages in the name of banks to induce users to click on links or reply to short messages, thus stealing personal information or funds.

3. Marketing information: Sometimes, banks will send marketing information to potential customers to promote their products or services.