I am sorry, but this is extremely inconsiderate towards smaller clients. I mean it's fine to add a new feature like MAPI, but why would you just remove something that works and supports older versions of Outlook? We are a smaller company (less than 20 users) and so I have to justify licensing cost on a yearly basis against competitors (Zoho Mail, Office 365, etc.) who offer more business relevant features (e.g. conversations to keep emails on the same subject sorted). We will certainly not add MAPI as a paid add-on, but sadly it seems that it is time to start looking for a replacement if this is true.