I accidentally sent some bitcoins to a testnet address from MtGOX. MtGOX accepted the transfer and deducted the balance from my account, but as far as I am aware it is impossible to actually send bitcoins on the live network to a testnet address. I have tried on my local bitcoin client and it won't allow it - the testnet address does not validate. Can someone please confirm if this is the case as MtGOX support staff seem unable to understand this concept.
Support summary:Hello. I accidentally sent xxxBTC to a testnet address nxxxxxxxxxxx on Wed 16 Nov 2011 06:37:42 PM GMT. I think (and hope) that this means that it will not actually be sent by your Bitcoin daemon as the daemon will not validate the address. If you could refund it I would be very grateful.
Thank you for contacting us. Unfortunately, BTC withdrawals are non-reversible within the system. If you wish, please contact the service provider of the address to see if you can get your BTC back. We apologize for any inconvenience caused.