If it was maintained by an email provider or company, I would have suggested you get on their case because the server is not properly configured, and that is why version 8.x of eM Client is not happy. As it is you who maintains it, I won’t suggest that . . .
I have been testing 8.1 and previews of 8.2 with Microsoft maintained Exchange servers and am not finding any issues, so it might be something in your particular server settings that is not compatible with the latest releases of eM Client. You did not say what version of 8.1 you tried but I assume it is the latest.
If you have a Pro License, I suggest you open a support ticket with eM Client. They will be able to interpret the logs and advise you further as to the cause.