user18196: I understand the reasons for wanting to use new change address for each transaction, but am unsure as to how they are treated by the Bitcoin core client. 

Is the address deleted as soon as the funds it received as change are spent?
The client probably doesn't watch for any further sends to these addresses, right?


user5406: Change addresses are no different than other addresses, except that they do not get shown in the UI, i.e. they are not visible in the recent transactions column. Just like all other addresses they will be checked for new balances whenever a new block is added to the database.
BitcoinCore keeps a number of unused addresses on hand of the size of keypool. The standard setting is 100 keys.
Whenever you create a transaction that doesn't spend a previous UTXO completely, the change gets sent to one of the previously unused addresses in the keypool, and a new address gets generated in the back of the keypool, to keep the number of unused addresses constant.
Likewise, when you request a "new receiving address" the first unused address from the keypool is popped, and a new one is generated and pushed in the back.
Even before the addresses are visible, the addresses are stored in the wallet.dat allowing you to create backups only every once in a while. (Well, you should at least every keypool transactions.)
Note: The keypool will only be refilled if the wallet is unlocked.

user6540: 
Is the address deleted as soon as the funds it received as change are spent? 

No, the change address is not deleted but it is stored as another of your key pairs of your wallet. Bassically when you make a transaction with 1 BTC spending only 0.7 the remaining 0.3 BTC is send to new address that is stored inside the client (current account) waiting for new transaction from operating "main" address to occur. 
Try yourself list your addresses (after you spend input on one of your change addreses) with command: listaddressgroupings

The client probably doesn't watch for any further sends to these addresses, right?

No, the client updates the balance on all keys inside the client. The change address can receive and sends BTC. The remaining funds will be updated as part of the main bitcoin address.
For more information see: Change on Bitcoin wiki

18196: <p>I understand the reasons for wanting to use new change address for each transaction, but am unsure as to how they are treated by the Bitcoin core client. </p>

<ol>
<li>Is the address deleted as soon as the funds it received as change are spent?</li>
<li>The client probably doesn't watch for any further sends to these addresses, right?</li>
</ol>
 5406: <p><strong>Change addresses are no different than other addresses, except that they do not get shown in the UI, i.e. they are not visible in the recent transactions column. Just like all other addresses they will be checked for new balances whenever a new block is added to the database.</strong></p>

<p>BitcoinCore keeps a number of unused addresses on hand of the size of <code>keypool</code>. The standard setting is 100 keys.</p>

<p>Whenever you create a transaction that doesn't spend a previous UTXO completely, the change gets sent to one of the previously unused addresses in the keypool, and a new address gets generated in the back of the keypool, to keep the number of unused addresses constant.</p>

<p>Likewise, when you request a "new receiving address" the first unused address from the <code>keypool</code> is popped, and a new one is generated and pushed in the back.</p>

<p>Even before the addresses are visible, the addresses are stored in the <code>wallet.dat</code> allowing you to create backups only every once in a while. (Well, you should at least every <code>keypool</code> transactions.)</p>

<p>Note: The keypool will only be refilled if the wallet is unlocked.</p>
 6540: <ol>
<li>Is the address deleted as soon as the funds it received as change are spent? </li>
</ol>

<p>No, the change address is not deleted but it is stored as another of your key pairs of your wallet. Bassically when you make a transaction with 1 BTC spending only 0.7 the remaining 0.3 BTC is send to <strong>new address</strong> that is stored inside the client (current account) waiting for new transaction from operating "main" address to occur. </p>

<p>Try yourself list your addresses (after you spend input on one of your change addreses) with command: <strong>listaddressgroupings</strong></p>

<ol start="2">
<li>The client probably doesn't watch for any further sends to these addresses, right?</li>
</ol>

<p>No, the client updates the balance on <strong>all keys</strong> inside the client. The change address can receive and sends BTC. The remaining funds will be updated as part of the main bitcoin address.</p>

<p>For more information see: <a href="https://en.bitcoin.it/wiki/Change" rel="nofollow">Change on Bitcoin wiki</a></p>
