Unfortunately it was too late to cancel the transaction, so there's just some hope left that he can manually assign the money to my account. Do you think thats possible? I sent him a picture with proof of my transaction and also I already sent some money from the same account so it should be clear to whom the money belongs.
I did the exact same thing last month. I typed "MTFOX xxx" instead of "MTGOX xxx"...
Anyway I shoot them an email and they transfered the money manually to my account.
Don't worry, they are just flooded with emails these days