No, it is not possible. Satoshi wouldn't be THAT stupid. Email isn't guaranteed to be transported encrypted, unless you encrypt your email yourself (metadata like email headers are likely to be transported unencrypted anyway).

At the times when Satoshi used his email address, it was highly unlikely that GMX used or provided an end-to-end encrypted mail infrastructure. You can bet that Satoshi knew this and therefore didn't treat his GMX mailbox as a vault where only he would've had access to its content.

Nobody sane would have his private keys touch foreign online devices!

Satoshi Nakamoto is still anonymous because he is smart.


As with every sad potential imposter of Satoshi or whoever claims to have access to one of his private keys: sign a message or STFU (and get medical and/or psychological help).