Can electronic invoices only be sent to qq mailbox?

No. There are many ways to send electronic invoices. You can mail it, add the attachment of the electronic invoice to the mail, and then send it to the recipient. You can also use chat software such as WeChat or QQ to send the electronic invoice to the other party's chat window, and the other party can receive it. You can also use file transfer tools such as Jianguo Cloud and Tencent Enterprise Mailbox to upload the electronic invoice to the file transfer tool and send it to the payee.