Follow this guide to configure a proxy server in nShift On-premises:

1. Go to Setup, click on Installation level, and choose New > Proxy Settings in the pane to the right. There are two options - one for client machines and one for the server.
   
   
   
   
2. There are 3 tabs in the Proxy Settings: Http, FTP and Smtp. nShift On-premises may use all three protocols depending on your configuration (carrier transmit, mailback, address validations/lookups, price calculation, etc).