I have purchased a used copy of Movie Edit Pro 2015, I can not use it as the previous owner regisrerd it using their Email address. How do I resolve this issue?
I think the only way in which this can be resolved is for you to ask the previous owner to log into his Magix account and deactivate the MEP 2015 registration. If he cannot do that via his account he will need to contact Magix Customer Support and ask them to deactivate the registration.
I am obviously assuming that you know who the previous owner is! If you do not know this you will have to contact Customer Support and ask if they can remove the existing registration details so that you can register the software. I suspect that you will need to provide irrefutable evidence that you have actually purchased the software and are not merely trying to use "for free" software that is registered to another user.