In Settings > Ship From Addresses unselect Use this address as the Return Address on my shipping labels. You can then add a Return Address that is different from your Ship From address.

This means that the postage costs will be calculated from your Physical Address, but any undeliverable packages will be sent to your Return Address. 

A screenshot showing the 'Ship From Addresses' section of Settings where you can enter or edit a Ship From Address. Towards the top, the physical address is shown. Below this section, there's a checkbox next to 'Use this address as the Return Address on my shipping labels.' When this checkbox is unchecked, an option for a separate return address appears below. In this section, you can enter an address that will be shown on the label, and this address will be used in the event that a package needs to get returned to the sender.

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