Awkward terminology: If I write an email, but I haven’t sent it yet, then it is correctly placed in a folder named “Draft”. However, if I click on Unread in the Global Folder, then my draft email is shown as an unread email that is actually absurd since I am the one writing it. Furthermore, when I click on the Draft folder then the emails are actually listed as items under a structure titled “Sent: Today (X items)”. This is pretty confusing, and I have more than once panicked because I suddenly thought that some ramblings in a draft had already been sent. I don’t remember ever experiencing that feeling when I was using Outlook.
I think you need to get some real business people involved. Technically your product is very appealing particularly because of you IMAP speed, but I sometimes get the feeling that the product has been designed by technical people.