This article gives detailed steps to fix search issues in Outlook for MacOS

Problem statement

Search in Outlook for MacOS does not show all emails. Unable to resolve even after re-indexing spotlight

Steps to resolve

1. Change permissions of all Mail folders

   Right-click on each mail folder (Inbox, Sent Items) and change from <User:Default Role:None> to <User:Default Role:Owner>

2. Quit Outlook and remove the file mentioned below so it rebuilds the database

   rm “~/Library/Group Containers/UBF8T346G9.Office/Outlook/Outlook 15 Profiles/Main Profile/data/Outlook.sqlite”

   Restart Outlook to rebuild the database, which will take a long time

3. Re-index Spotlight for Outlook messages

   Add the Main Profile folder to Spotlight privacy, wait 15 minutes and remove Main Profile from Privacy (~/Library/Group Containers/UBF8T346G9.Office/Outlook/Outlook 15 Profiles/Main Profile)