Fix indexing for search in Outlook
Sometimes when migrating emails, rebuilding PST files, and enabling additional mailboxes the Outlook search index can fail to update or even become corrupted. This isn’t something that happens too often, but if you are frequently moving emails between different computers, then the odds drastically go up. Most problems with the search index can be fixed by deleting and rebuilding it, so let’s do that!
At the right side of the right pane, click the Indexing Options button.
Back on the Indexing Options window the status will update at the top. It should start out with showing the items currently indexed and the status of the index rate below it. If you have other applications running in the background then it will display a message saying “indexing speed is reduced due to user activity.”
Once Outlook finishes building the index it will say that Indexing is complete in the status window.