Microsoft has officially acknowledged -- though not yet fixed -- a problem with the Feb. 16 edition of Office 2016 Click-to-Run, version 16.0.6568.2025. Customers now report that you may have to manually revert all the way back to the Dec. 8 edition of Office 365 -- version 16.0.6001.1043 -- to get Outlook to work properly with POP3 mail accounts.
Microsoft engineer Dan V describes the problem this way:
If you have the most recent Office 365 update installed (version 16.0.6568.2025), your emails may get deleted from the server or you may receive duplicate emails in your inbox.
KB 3145116 goes into greater detail, saying, "After Outlook downloads your email, all the email messages on the server are deleted from the Inbox," and "email messages are downloaded multiple times in Outlook, causing duplicate items."
The KB article goes on to say:
This issue may occur if you have Outlook 2016 version 16.0.6568.2025 configured to use POP3, and if you have the Leave a copy of messages on the Server option enabled…
If you have the option Remove from server after <x> days enabled, you may experience the issue of email messages being deleted from the server.
If you have the option Remove from server after <x> days disabled, you may experience the issue of email messages being duplicated in Outlook.
Microsoft is researching this problem and will post more information in this article when the information becomes available.
Instructions for changing from POP3 to IMAP mail access or for moving back to an earlier version of Office 365 are in the KB article. Diane Poremsky has a more thorough explanation of rolling back Click-to-Run versions on the Slipstick site.
We've seen the same sort of problem crop up recently with Office Click-to-Run. The Dec. 11 change to 16.0.6366.2036 wiped out Word customizations. It took Microsoft more than a month to fix that problem, which it finally did with the Jan. 12 release of 16.0.6366.2056.
This problem has an entirely different etiology from the problem I reported this morning with the latest cumulative update to Windows 10. But both issues point to the same villain: Microsoft isn't able (or willing) to change its "as a service" offerings quickly enough to cope with significant problems.
It's a congenital defect. If Microsoft pulls the patch, anyone running the Click-to-Run version of Office 365 will continue to run the same, aberrant version until they restart Office and receive the next (or possibly the previous?) version. Thus, for a certain nonzero stretch of time, two different versions of Office will be out in full force -- anathema to the "as a service" mind-set.
When Windows or Office start throwing curve balls, life gets very interesting, very quickly.