this idea for those ppl who putting email for them accounts its working as this
1- if anyone try to changing ID or Password that ID email get email about that if he agree to change his ID or Password.
2-if anyone try to log on by other phone or PC another that really player using he get an email there are someone using his account or maybe that other phone/PC can't enter till really player agree.
*these steps make really sure for ur rules don't breaking by players like trade or sharing accounts maybe not all but 85%