Satoshi Nakamoto Identity GMX Email Account

Satoshi often used a GMX account for his communications. Was it not theoretically possible to determine his identity via his IP address, even many years later?

I wonder to what extent one does not have to assume that, for example, American intelligence services know Satoshi's true identity. After all, an increased interest should have existed since 2014 at the latest.

Do we have to assume that only at the moment for the public domain his identity is unknown, but history will eventfully fill this gab?