How to: Test a Form in Run Time
Forms customized with form regions
You cannot test forms customized with form regions from inside Outlook. You must save the form as an .ofs file, update the add-ins used with the form regions, and restart Outlook. For more information, see How to: Create a Form Region.
Forms customized with form pages
To switch between the design mode and the run mode (that is, as the form appears when used) of the form, in the Forms Designer, on the Developer tab, in the Form group, click Run This Form.
Note You can test the form outside the Microsoft Outlook design environment by opening a new instance of the form. Enter information in the form, send or post it, and then open the form to make sure it appears correctly.