Outlook slow updating cached messages
In Windows 10 it is : Click the Start menu and select Settings.
One of our users complains that he cannot synchronize mail from his Mailbox in the cloud (Exchange Online).
This should have fixed your Outlook 2016 search problems.
These issues could have many different roots, and can be fixed by doing different things. When dealing with Microsoft Outlook Search not working, it is important to just keep calm and follow the steps provided here.In previous versions of Outlook, you could specify which mailbox or .pst/files within Outlook to index, but in Outlook 2016 you either index Outlook completely or you do not index it at all.When you check if it is marked for indexing, you should also try disabling and then re-enabling Outlook.Afterward, you can return the sleep time to something normal.I keep emails for long periods to facilitate searches for old messages and have very large in and sent boxes.