Microsoft Outlook uses folders to contain collections of data. An Outlook folder is where items, such as your new e-mail messages (Inbox), sent e-mail messages (Sent Items), or e-mail messages you want to save are stored. Messages are not stored in Search Folders. Search Folders are virtual folders that contain views of all e-mail items matching specific search criteria.
Search Folders display the results of previously defined search queries. The e-mail messages shown remain stored in one or more Outlook folders.
In Mail, in the Navigation Pane (Navigation Pane: The column on the left side of the Outlook window that includes buttons for the Mail, Calendar, and Tasks views and the folders within each view. Click a folder to show the items in the folder.), there are three default Search Folders — For Follow Up, Large Mail, and Unread Mail. Any e-mail item with a flag appears in the For Follow Up Search Folder. E-mail items that are larger than 100 kilobytes (KB) appear in the Large Mail Search Folder. All unread e-mail items appear in the Unread Mail Search Folder. These three default Search Folders can be modified or deleted.
When you create a Search Folder, you have a number of options to choose from, such as "Mail with attachments" or "Mail from specific people." You can also create your own custom Search Folders, defining specific search criteria that e-mail messages must meet to be displayed in the Search Folder. Each Search Folder is a saved search that is kept up-to-date, monitoring all of your folders for any item that matches the search criteria of the Search Folder.
Important When you delete a Search Folder, the e-mail messages shown in the Search Folder are not deleted, because those items are never saved, only viewed, in a Search Folder. However, if you open or select one or more e-mail messages shown in a Search Folder and delete the e-mail messages, the messages will be deleted from the Outlook folder where they are stored.