In this example, I’ll show you how to use a built-in form as the starting point for a custom form. This walk-through shows how easy it is to set up your own custom forms. Change theme colors Outlook. Many forms will also work as templates, saved using the File, Save as menu. Spaatz. I want to. .pst File Microsoft Outlook (non-Exchange Server) uses files with the extension .pst to store your e-mail messages, calendar, contacts, and other information to your computer. You must base all custom forms in Microsoft Outlook on standard forms. Below is the embeded version (using an