Hello @ShakeHobbies!
First, welcome to the Community—we’re so glad you're here! This is a great space to find answers, share feedback, and suggest new product features. We hope you find it both helpful and inspiring!
Your question may refer to USPS First-Class Mail. After reviewing our USPS by ShipStation Help Center article, I can confirm that it is supported.
That article also includes a full list of available services, package types, and confirmation options, which should help you select the right service for your needs.
Let us know if you have any other questions—we’re happy to help!
Happy Shipping!
-Cara
