The latest windows update for Outlook 2016 causes issues if you are using it for POP3 accounts. Build 16.0.6568.2025 is causing problems for people who have Outlook set to leave mail on the server for a period of time. Instead of deleting the aged mail from the server, it deletes all of the mail. However, if users uncheck the option to delete mail after a period of days, while leaving the “leave on server’ setting checked, this will leave all email on the server. To do this, go to File, Account Settings, double click on the POP account then click More Settings. The leave on server setting is on the Advanced tab.
The second issue with this update is that POP3 mail left on the server keeps downloading, over and over, casuing multiple copies of the same email to appear in your Inbox.
The Fix : (temporary!)
First, go to File, Office Account, Update Options and Disable updates then create an appointment on your calendar to re-enable updates next month.
To revert to the February 9 2016 build 16.0.6366.2068, open a command prompt as Administrator and type or paste this command line in the Command Prompt window:
“C:\Program Files\Common Files\Microsoft Shared\ClickToRunofficec2rclient.exe” /update user updatetoversion=16.0.6366.2068″
(Don’t forget the inverted commas )