When searching for a particular message, you might remember that it contained an attachment, was marked important, or was received last week. To find a message based on certain criteria, the Filter Email command provides fast access to the most frequently used Instant Searches.
Click Home, and then in the Find group, click Filter Email.
When you use a filter, the same Search Tools tab appears on the ribbon as when you click in the Instant Search box.
To clear the search results and view all items in the selected mail folder, click in the Instant Search box, or on the Search tab, in the Close group, click Close Search.
In the Instant Search box, click to clear the search results
Tip: The Outlook Junk Email Filter is a different feature. For more information, see Overview of the Junk Email Filter.