What is the impact of imessage without an address?

1. If you don't have an address, you can add it to the address book or enter it manually. Otherwise, you can't use iMessage, the sending fails or you automatically switch to SMS.

2. The use of iMessage is similar to that of ordinary SMS. The receiver needs to receive the address, and the other party also uses the Apple device to turn on the iMessage switch. The only difference is that it uses traffic to send without deducting the SMS fee.