In Microsoft 365, Microsoft Search returns search results based on the context of the application that you are searching from. When searching in Outlook, Microsoft Search is used to search email messages that are in your mailbox. There are plans for later builds to also query the Calendar, files, and other items within Outlook.
It’s hard to imagine an Outlook without search. In its earliest versions, Outlook supported basic filters based on MAPI restrictions. Starting with Outlook 2007, Outlook has utilized Windows Desktop Search (WDS) to index Outlook Data (.pst) and Offline Outlook Data (.ost) files. These data files are normally stored on the local disk, as are the WDS search indexes. Although WDS provides excellent performance using the indexes on the local disk, mailbox sizes have increased while less mailbox data is synchronized to the local disk. This shift has resulted in a clear need for server- and service-powered search solutions.
This is where Microsoft Search comes into the picture. It fully indexes and searches content, while providing rich and intelligent search features that have become an industry norm. Throughout this journey, Outlook has evolved from local and MAPI-restriction searches, to server-based Exchange content indexing, to EWS/FAST search, and now to the most recent service-based iteration, Microsoft Search.
This section is organized to help you determine which search solution is being used, based on a specific scenario. The Outlook product group is updating current versions of Outlook desktop, web, and mobile clients to migrate more and more scenarios to use Microsoft Search.
Note If Outlook cannot connect to Microsoft Search, an error message is displayed with a link to perform a local search.
The following tables list Outlook for Windows search scenarios, along with their current status and future plans to onboard them onto Microsoft Search.