This article covers how to set the Windows version of Microsoft Outlook 365 so that it will automatically search ALL Mailboxes, rather than just the current mailbox.
STEP 1: Within Microsoft Outlook locate the Mailbox Search Field / Bar at the top of the application window and click inside of the Search Bar, which will bring up the Search Bar Menu beneath in the Menu Ribbon.
STEP 2: You may need to expand your menu by clicking on the three horizontal dots [ … ] to see the “Search Tools” menu under Options. From there click on “Search Options…” from the context menu.
STEP 3: The Outlook Options window will appear from which you may select the “All mailboxes” radio option under the Results section. Click OK to save these settings.
I hope my article on defaulting Outlook Search to search All Mailboxes has helped you. I welcome your thoughts, questions or suggestions regarding this article.
Let me know if you found any errors within my article or if I may further assist you by answering any additional questions you may have.