Bitcoins sent to Invalid address. Where does it go?

[MAC]

A friend of mine recently sent 5 BTC to an address that was used by one of her accounts a week or so ago. That account auto changes the funding address for protection. So I am wondering  the following:

Where did the 5 BTC go?
Will it come back if found to be invalid?
Are old addresses reused?
 

[CIYAM]

The situation will very much depend upon the service in question (where is the account held?) but in general a Bitcoin address that "belongs" to an account should always be valid and still tied to that account (even if the service allocates a new address for usage as this is done to help protect your anonymity).

[jl2012]

A friend of mine recently sent 5 BTC to an address that was used by one of her accounts a week or so ago. That account auto changes the funding address for protection. So I am wondering  the following:

Where did the 5 BTC go?
Will it come back if found to be invalid?
Are old addresses reused?
 

All you have to do is to ask the service provider

[MAC]

Thank you both for the quick answers. The site she thinks they may have gone to is currently down. So that's adding to the angste. I'll update you all when we figure it out.

[CIYAM]

I expect the funds will turn up when they are back online (hopefully) so don't stress out.

[kokojie]

A friend of mine recently sent 5 BTC to an address that was used by one of her accounts a week or so ago. That account auto changes the funding address for protection. So I am wondering  the following:

Where did the 5 BTC go?
Will it come back if found to be invalid?
Are old addresses reused?
 

As long as that address is owned by someone, then it's recoverable. If the address is truly invalid (private key unknown to anyone), then you can't get it back.

[Otoh]

SWC is back up now if that's the site you used.

[MAC]

Ok, so it was indeed SWC. They finally admitted they made a mistake and graciously added an additional coin to her total balance.

[Otoh]

Glad to hear it got resolved in a good way, to be clear an invalid bitcoin address is one where the check sum doesn't add up correctly (no private keys exist for them) & it is impossible to send to these so funds can never go in to the void that way, what you were referring to was an old deposit address that was used in error - in the case of Mt. Gox for example they issue new ones to you for each transaction (for privacy) but you can still actually use an old one of these & it will work fine, it just depends on how the service you are using set their systems up.

What you don't want to do is send funds to a valid btc address where the private key is unknown or has been discarded then those funds will be stuck there & are effectively lost unless the private key for that address is subsequently found to not have been irrevocably deleted from where ever it had been stored.

http://blockexplorer.com/address/1BitcoinEaterAddressDontSendf59kuE   <--- valid btc address with unknown private key = lost

http://blockexplorer.com/address/1AnyOldBolloxWithInvalidCharsOIl0OI   <--- invalid btc address with invalid chars: OIl0 = can't send to

http://blockexplorer.com/address/1BitcoinEaterAddressDontSendf59kuF   <--- invalid btc address, check sum fail = can't send to   

[johnvolta]

Nice to know, issue got resolved