Outlook 2016 POP3 duplicate email

Update:

This issue has been solved in the March 4 update for Office 365, version 16.0.6568.2036. To get this fix directly, in Outlook choose: File-> Office Account-> Update Options-> Update Now. If you’ve previously disabled updates, you’ll first have to choose “Enable Updates”.

After updating, you may receive duplicates from the mail server one last time.

After applying a February 16 update for Office 365, version 16.0.6568.2025, you may encounter the following issues in Outlook 2016 when you are using a POP3 email account.

• When you have the POP3 account configured to leave a copy of the emails on the mail server for x days, the setting is not being respected and all emails are deleted from the mail server regardless.
• When you have the POP3 account configured to leave all of the emails on the mail server, the emails are repeatedly being downloaded and thus cause duplicates.

Microsoft is working on a fix but in the meantime, you can use one of the following workarounds.

• Configure your POP3 account not to delete it after X days but leave a copy on the mail server (in some cases, you’ll then end up getting the second issue).
• Configure your POP3 account to not keep a copy on the mail server.
• Configure your account as an IMAP account instead of a POP3 account.
• Uninstall the update by rolling back to version 16.0.6366.2068 or even earlier.

Uninstalling the update

Before uninstalling the update, disable automatic updates via:
File-> Office Account-> Update Options-> Disable Updates

Additionally, create a reminder in your Calendar to re-enable updates in April as a fix for this issue should be deployed by then.

To uninstall the update and revert to the February 9 build, open a Command Prompt as an Administrator and run the following command:

"C:\Program Files\Common Files\microsoft shared\ClickToRun\OfficeC2RClient.exe" /update user updatetoversion=16.0.6366.2068

If you get an error when trying to revert to this build, revert to the January 25 build instead:

"C:\Program Files\Common Files\microsoft shared\ClickToRun\OfficeC2RClient.exe" /update user updatetoversion=16.0.6366.2062