Quote from: Vinz87 on March 15, 2014, 12:47:16 PM

Update: the transaction was broadcasted through blockchain.info API, and after 2 days I received an email from them saying they will cancel the transaction since it is not going to be confirmed.

My watch-only Electrum wallet still has it pending in transactions history.

When, and how, will I know that those coins are again in my sending address and I'm able to spend them in another transaction?

If you are going to be playing around with rawtransactions, then you need to understand that there are no "coins". There is also no "sending address". There are only transactions. Therefore, asking "When, and how, will I know that those coins are again in my sending address" is an unanswerable question.

You have unspent outputs that you attempted to spend when you created the transaction. The transaction attempted to create new unspent outputs that can only be spent with signatures from particular private keys. Then you attempted to broadcast the transaction.

There are multiple places that the transaction could exist once you attempt to broadcast it. It could be stored in your wallet. It could be stored by any peers that hear about it. It could be stored by any miners. It could be stored in the blockchain.info database.

If you try to create a new transaction that spends any of the same unspent inputs as were spent by the transaction that you broadcast, any of those places will simply ignore the new transaction if they still know about the old transaction (blockchain.info may store both transactions and create an indication on their webpage that both transactions are a "double-spend attempt").

If you stop your client from broadcasting the transaction, after a while, peers, miners, and blockchain.info will independently drop the unconfirmed transaction from their memory. There is no easy way to determine which (if any) peers or miners have dropped the transaction from memory at any time.

Once you make sure that your client is no longer attempting to re-broadcast the transaction (by removing the transaction from your client), you can wait a few days. Generally after a few days you can assume that most peers and miners have dropped the old transaction and will be willing/able to receive and relay the new one.

There is no guarantee that the old transaction will be dropped. Any peer on the network can re-broadcast the old transaction at any time if they want to. Generally, peers don't re-broadcast transactions that didn't originate from their node, but there is nothing stopping them from doing so if someone decides that they want to.