PostBank’s invitation to upgrade the card and increase the limit is a marketing tool, and its authenticity requires customers to judge carefully. If you receive such an invitation card, you can first check whether the sender is Postal Bank and confirm whether the content of the email is reasonable, and then call the bank's customer service number for verification. Do not disclose personal information or perform any operations before confirming the authenticity of the email. At the same time, customers are advised to follow a reasonable consumption plan when using credit cards to avoid repayment difficulties due to high credit limits.