I do not even know why I need to explain myself AFTER I've posted an SIGNED and a verified message from an old btc address. 
Because account sellers sometimes will offer an account with the private key to an old address included. Your account has its email recently changed and has been inactive a long time so it looks suspicious. I'm not saying you definitely did buy the account just that isn't really proof.
That's true. I recently changed my e-mail address because I no longer have access to my old e-mail address.
That's why I've added my new e-mail address to be on the safe side.
A signed message from an old bitcoin address is a standard procedure to prove that the account belongs to me.
I would not know how else I could verify my account. I can talk to you in German if it helps you (just kidding
). As I said, this account has never changed the owner and will never change the owner!