

The Test-ExchangeSearch cmdlet is used to diagnose problems with the Exchange Search service. If your Outlook doesn’t search your mailbox when using the Exchange Search Index, the problem is most likely with the Exchange server. The MSExchangeSearch service indexes an email message as soon as it gets into the mailbox database on the server. If Cached Exchange Mode is disabled, mailbox-side index (maintained by Microsoft Exchange Search Indexer) is used for mailbox searches. If Cached Exchange Mode is enabled in Outlook, the local index on your computer is used to search items. In this section, we’ll take a look at how Outlook search works if your mailbox is located on an Exchange server or Exchange Online (Microsoft 365).

In the properties of Outlook OST and PST files, make sure that their indexing is allowed (it is worth doing regardless of their indexing being already enabled in Windows Search Service settings).


If you haven’t made significant configuration changes in Outlook for a long time and indexing is still ongoing, then the problem with the Outlook index is obvious. If you have recently (up to 3-4 hours) performed these operations, you need to wait until indexing is complete. The Outlook search index is rebuilt when you add a new mailbox or Outlook Personal Folder (PST) file, move emails between folders, etc. Outlook is currently indexing your items.
