If you find that you are unable to delete email(s) in Microsoft Outlook 2016 this is a known issue when using an IMAP account that can be easily resolved.

Under Folder > Purge > Purge Options check both of the boxes at the bottom of those settings in the Deleted Items section (“Mark items for deletion but do not move them automatically” and “Purge items when switching folders while online“) to make emails marked for deletion actually disappear from your Inbox.

Posted in: Email