After you've registered with USPS by following the steps under Choose Carrier in your Admin Area (Settings > Shipping), you will need to contact USPS again and give them the following information,either via email (email@example.com) or by phone (1-800-344-7779):
I am using a third party eCommerce software called Volusion, my account number is XXXXXX, please give my account access to the USPS ExpressMailLabel API. I will not be altering the labels. I will also need access to the USPS Delivery Confirmation V3.
NOTE: Be sure to replace "XXXXXX" with your username.
In some cases, USPS will advise you already have access to the production server. While this is necessary to receive live rates, it is only part of the access needed to print shipping labels. Until USPS has provided access to the label printing functions of their API, you will not be able to print labels.
In other cases, they will refer you back to Volusion, advising that:
There is a line of code that refers to "shippingapitest.dll". You'll need to remove the word "test".
We have already performed that process. We have this file available on each server that hosts our stores and it is shared among them.
At this point, it is up to USPS to finish the process and provide access to the label printing functions. There is nothing further that needs to be done on the Volusion side and nothing more you, as a merchant, can do. This process MUST be completed by the USPS.
Lastly, per the USPS, the only shipping methods that offer printable labels are the following:
- Priority Mail® (domestic)
- Priority Mail Express™ (domestic)
- First-Class Mail® Parcel (domestic)
- Priority Mail International®
- Priority Mail Express International™
- First-Class Package International Service®
Outside of these shipping methods, no other labels may be printed.
Note: These labels are shipping, not postage, labels.