Mail Delivered is a principle that will allow you to send impossible prediction emails to your spectator's phone/computer.

Effect:

Imagine that at the beginning of your performance, you send a prediction email to the spectator which they can check and acknowledge.

Then when your routine is finished, the spectator reads the email (the same email sent to them at the beginning of performance) and the prediction matches with whatever choices spectator has made during the routine.

This is a super direct piece of mentalism that will allow you to predict anything in an impossible condition.