I just started using bitcoin a few months ago. I recently had an issue where I made a bitcoin withdrawal from one account to my deposit address for another account. The bitcoin account where I made the withdrawal took several hours to process the withdrawal. The bitcoin account where I was depositing the money only allows 15 minutes for the transaction before a new address must be generated. So because the withdrawal was processed past that 15 minutes, the money was not credited to my account. I ended up having to email the company with the account I deposited to in order to resolve the issue. Luckily, it was a small amount of money, so the ordeal wasn't too stressful. But I do plan to transfer with larger amounts of bitcoins, so I want to know how to avoid this when dealing with accounts that require payment to be received within 15 minutes after generating a deposit address.