: This is your only proof of purchase and is required to track or replace a lost order. Online Alternatives
Since you can't buy them online, here is the standard process for getting one at the Post Office: buy postal money order online
: You can buy domestic money orders for any amount up to $1,000. : This is your only proof of purchase
: Write the recipient's name immediately to prevent anyone else from cashing it if it's lost. buy postal money order online
If you need to send money digitally without visiting a physical location, consider these online-only services: Sending Money Orders - USPS