What's the matter with iphone5 sending text messages automatically?

It is very likely that your APPLE ID was leaked, and someone logged into your account and sent a text message.

If your mobile phone has a similar situation, you can try to do the following:

1. Turn off iMessage, turn on phone settings, select information and turn off iMessage;

2. Modify your Apple ID password in time and log in to iTunes to modify it. The password cannot be too simple;

3. Change the Apple ID again, and click the email address in the phone settings-information-sending and receiving to change the account again.