What happens if you initiate a transaction to a non-existent address in geth? Is there any way to determine if an account exists as a legal address?
Hope you can give me some help, thanks!
There is no official checksum for Ethereum addresses, which means that any combination of 40 hex chars (excluding 0x) is a valid address.
(...) convert the address to hex, but if the ith digit is a letter (ie. it's one of abcdef) print it in uppercase if the ith bit of the hash of the address (in binary form) is 1 otherwise print it in lowercase.
Before sending any transaction, you could check whether the target address follows the EIP-55 pattern. But be warned: if it doesn't follow, it doesn't mean it is an invalid address, as goodvibration pointed out in his comment.