Quote from: Zerbie on September 22, 2011, 11:22:20 AM

SOLUTION: Wrap the send packet with the receiving BitCoin address, so only the receiving BitCoin client can un-encrypt the packet and transmit the packet back out to the network. Thus, the sender can be assured he is sending it to a real client.

If you don't require the receiver to be online, then this would add a level of complexity to the Bitcoin system. The transaction needs to persist somehow until the receiver gets online.

(EDIT: You probably want to define a TTL in any case. The coins need to be blocked for the duration of TTL, otherwise the wrapped packet will be invalid.)

Quote from: cbeast on September 22, 2011, 11:38:33 AM

If you have your wallet backed up, you can just restore your backup wallet.dat. Since the last transaction is not verified, your bitcoins will not be spent.

If you enter a broken address, there is a good chance that the transaction will not happen in the first place (because of the checksum). I think he's talking about cases where a transaction goes out, in which case it will surely get confirmed.