You can only see IP of the abuser if they made a post in your forum, that is how phpBB works.

I suggest you delete the user, also ban his email address

E-mail address: * [email protected]

To ban this email address, add

*@hotmail.net

hotmail.net is real email or fake ?

How use got activated with a fake email ?

You need to set user activation to User or Admin (so only email verified users can login to your forum and post.)