You need to add mail-tags to the fields in the Mail tab. These tags need to correspond to form-tags used in the Form tab. For example, when you used a form-tag
[text your-new-field], the corresponding mail-tag that you should use in the Mail tab should be
[your-new-field]. For more details, see How Tags Work.
A mail-tag in the Mail tab will be replaced with the user input to the corresponding form field.