How can I have a USPS shipping label automatically generated each time a customer places an order on my website?
Get a PNG of an empty label,and use ezPDF to autofill the fields and generate a PDF that you can print.
How long is a piece of string?
Do you just want the labels generated and stored? Do you want them sent directly to a printer? Do you want them emailed?
Your question needs to provide more background information.