*HELP* Can BTC be sent to an invalid address?

[dripdropdead]

I withdrew BTC from an online exchange however (carelessly) had input an invalid receiving address (it was a Blackcoin wallet address).
From my previous experience, a pop-up "invalid address" would usually appear and the transaction can't proceed.

Unfortunately, this online exchange processed it and the current status says "COMPLETE:ERROR".

I have filed a ticket but am really anxious about the situation.

Is it possible that BTC can be sent to an invalid address? Will they be "lost"?
I've tried to send a small amount from my blockchain.info wallet to the invalid address but it wasn't possible.

I would appreciate your insights, thanks.

[Rannasha]

Bitcoin addresses contain a checksum which makes a mistyped address only be valid in 1 in 4 billion cases. Trying to send coins to an invalid address will fail. However, the exchange you use may not check for such a failure correctly and it may deduct the amount you tried to send from your balance even though the transaction failed. If this is the case, you should contact the exchange and get them to fix the issue.

[dripdropdead]

Bitcoin addresses contain a checksum which makes a mistyped address only be valid in 1 in 4 billion cases. Trying to send coins to an invalid address will fail. However, the exchange you use may not check for such a failure correctly and it may deduct the amount you tried to send from your balance even though the transaction failed. If this is the case, you should contact the exchange and get them to fix the issue.

I'm pretty sure the checksum didn't sum up as I manually tried to send 1 satoshi to the invalid address but it failed.

That being said, I could probably conclude the said BTC was never successfully sent nor "lost" in the process.
It is now up to the integrity of the online exchange to refund it to my balance. Wish me luck 

Thanks!

[Abdussamad]

I withdrew BTC from an online exchange however (carelessly) had input an invalid receiving address (it was a Blackcoin wallet address).
From my previous experience, a pop-up "invalid address" would usually appear and the transaction can't proceed.

Unfortunately, this online exchange processed it and the current status says "COMPLETE:ERROR".

I have filed a ticket but am really anxious about the situation.

Is it possible that BTC can be sent to an invalid address? Will they be "lost"?
I've tried to send a small amount from my blockchain.info wallet to the invalid address but it wasn't possible.

I would appreciate your insights, thanks.

blackcoin addresses start with a b. bitcoin addresses start with 1 or 3 in the case of multisig addresses. The address you entered was an invalid one for bitcoin and you got an error message. If I were to take a stab in the dark I would say the coins were never sent.