Use Activesync to Office 365

We use Office 365 but we only allow Activesync connections, all others are blocked (IMAP, POP and EWS). I have configured the account as “” and then changed the server to (also tried It seems like its connecting and then I get a “503 Server Unavailable” message.

Any thoughts?

Unfortunately ActiveSync is not supported for use with Exchange server, this protocol is designed for mobile devices thus it is not possible to use it with eM Client. In order to synchronise your account with eM Client, please make sure to allow any of the other protocols used for server sync.


Hmm - it seems to have just randomly started working - perhaps MS were having yet another issue.

Glad it works, make sure to let us know when you come across any other issues or questions about the application, however please note that ActiveSync is not supported for your server and thus can generate issues.


Paul - Activesync is designed for remote devices (not necessarily mobile).  Windows Mail, built into ALL Windows 8,8.1 machines uses activesync as its protocol and is available on Desktops and Laptops.  Is there some reason why this scenario isn’t supported? this would be a compelling reason to use EM Client over the free in-built Windows Mail (which uses Activesync).

If you have seen the recently released Windows Mail (or whatever it is now called) that comes with Windows 10 then you will see why we need a replacement.  I suspect you’ll see a lot more people come to EM Client shortly, especially if you can properly support Activesync and make yourself a direct replacement for Windows Mail.

Also - the other protocols are not allowed as each of them introduce some form of security risk that can be better mitigated by only allowing the use of Activesync (which requires a user/pass, and, for the device to be whitelisted by the remote server).

It works but I randomly get this error “MailExceptions.OperationException: Error in client/server conversation” and I have to keep hitting ignore on it

As I suggested, this is not supported, I’m sorry it’s not possible to workaround this error while using AirSync/ActiveSync with your mail server.