Started wit an unread count issue which is sorted now. But ended up with two other issues mentioned in the topic title. Maybe better to open separate post. Earlier information can be found here: https://forum.emclient.com/emclient/t…
Testing for my company if we can safely move away from Outlook. But so far too many issues. Ultimately we also will replace Exchange for probably Axigen but first the client needs to be stable enough.
Duplicate issue seems to be sorted now. Also i stell do have sent items in my Hotmail and Exchange accounts, don’t get why this option is on by default than anyway. 
Hello Christian,
we are aware of this issue with Exchange accounts.
This option is on by default for accounts that do not support saving of Sent messages (for example POP accounts).
Most other servers are able to pair the sent copy with their own, but we found that recently the Exchange protocol is having trouble with it.
Sorry for the inconvenience.
Regards,
Olivia