Hi,
Whether you can search for Outlook items from Start depend on the version of Outlook and Windows you are using. If you are using Outlook 2013 or Windows 8/Windows 8.1, I'm afraid the searching from Start feature is dropped. See:
"In Office 2013, Outlook items do not display in Windows Shell searches (for example, searches from the Start Menu or by using Win+F). Perform Office searches within Office 2013."
I'll collect and report your question through internal way. Although revisions cannot be made to the application, your feedback is appreciated. It will help improve later versions of these products.
Steve Fan
TechNet Community Support