If your original credit card bill is in another mailbox, and now you want to transfer to QQ mailbox, there is a function that can be realized. The specific steps are as follows:

1. Log in to the web version of mail.qq.com with a computer browser, then click Settings in the upper left corner, select other mailboxes, add other mailboxes, enter the addresses and passwords of other mailboxes, and bind successfully after verification (Note: if it is not a QQ mailbox, you need to fill in the pop3 addresses of other mailboxes, which Baidu will generally know), so that you can receive emails on behalf of mailboxes, as shown in the figure:

I hope it helps you!