When you cancel a label in ShippingEasy that was generated through Endicia, a refund is automatically requested. However, it can take a couple of weeks to process the refund. Once approved, your refund(s) will be automatically deposited into your postage balance.
USPS requires 10 business days to process the postage refund on their end, as they need to ensure that the tracking number for the cancelled label doesn't subsequently show up in the mail stream. So, Endicia will wait 10 days to begin processing the refund. It then takes Endicia another 4-10 days to finalize the refund.
Within 20 days from cancelling a shipment, the shipping paid will be refunded back to your postage balance.