While a large portion of the labels generated in ShipStation is shipped via the USPS, ShipStation doesn't offer a direct integration to a USPS account. Instead, ShipStation offers a complementary integration with USPS label provider Stamps.com which is available to all US-based ShipStation accounts.
Following the steps below, you'll be able to create your very own complimentary Stamps.com account within ShipStation.
You're also more than welcome to connect an existing Stamps.com account to ShipStation. It will convert to a complimentary "ShipStation Pro Plan $0" on your next month's Stamps.com billing cycle.
Creating a Complimentary Stamps.com Account in ShipStation
Go to your Account Settings (the wrench icon in the upper right).
Next, select Shipping and then Carriers & Fulfillment from the sidebar on the left.
Click on Add a Provider Account.
On the popup that appears, select the UNITED STATES POSTAL SERVICE BY STAMPS.COM box in the top left-hand side.
Click the green Connect button in the lower righthand side of the popup, and continue to the Get Started page.
Fill in the fields on the Create Your Stamps.com Account page.
Click Create Free Account and you'll be able to ship with the USPS!
For more information on what this Stamps.com account will offer, check out our Stamps.com partner page.
When you create a complimentary Stamps.com account through ShipStation, Stamps.com generates an account name and password for you. You can view your account name by going to ShipStation's Settings > Shipping > Carriers & Fulfillment and clicking Account Settings for the Stamps.com account.
This window provides your account username, which you will need should you ever contact Stamps.com directly about your account.
You can also access your Stamps.com account settings, reports, and SCAN forms directly through this window.
Resetting your Stamps.com Password
One thing to keep in mind is that ShipStation does not generate your password, does not have access to it, and cannot reset it.
Should you ever need to reset your Stamps.com password, you will need to contact Stamps.com customer care at 1‑855‑860‑7867 (Hours: M-F, 6am to 6pm PT).
Once your password has been reset by Stamps.com, use the Reauthorize button in ShipStation's settings to enter your new Stamps.com password so you can continue to create Stamps.com labels.
For more information about resetting your password, see reset my Stamps.com password in ShipStation.