ShipStation actually uses a wide range of IP addresses to communicate with your store, which is why we recommend using your application URL (e.g. ss2.shipstation.com; ss3.shipstation.com; ss4.shipstation.com; etc.) for any whitelist or security program you may be using with your store.
However, should you use a security application that does require IP addresses, please contact ShipStation Technical Support. We can provide you with the range of IP addresses necessary for your account.
Just click the Contact Us link on the bottom of this page to submit a support ticket with your request.