08/03/2016 – UPDATE – Microsoft have released a patch so please update your version of Outlook (see the MS KB link below for instructions).
Users of Outlook 2016 who have a POP account are finding their emails are being duplicated or in some cases being deleted.
At the time of this post Microsoft have not patched this bug and suggest either changing to IMAP or rolling back to an earlier version of Outlook 2016. Please find the Microsoft Knowledge Base article here: http://support.microsoft.com/en-us/kb/3145116
This only appears to affect POP mail users who have “Leave a copy of messages on the server” selected. If you also have “Remove after X days” selected then your emails will be deleted, if you do not have this selected then your emails will be duplicated.