I have a user connecting to our SM 16.2.6422 with Outlook 2013 over EAS that is having an issue when deleting a single instance of a recurring calendar event. The event deletes from the local Outlook calendar, but it remains on the SmarterMail server side when viewed from the Web UI as well as in Outlook for another user who has been granted shared access to his calendar. Deletion and creation of single calendar events work fine and synchronize across to the user with shared calendar access.
I'm mostly trying to figure out if this is an issue with Outlook or SmarterMail (I'm leaning toward SM). If it is a SmarterMail bug whether it's known and if it's on the roadmap to be fixed.