EWS not on 443

How is it possible to add an ews account without the testing? i have one public ip and i must use 443 for a different service, so i must use a not standard port.
When i try to add the account, i enter the emailadress, username and password. The assistent says that he found the server, but cant login.

Hi Max, unfortunately it is not possible to setup an Exchange Web Services account using your specified port, as eM Client is only using the autodiscover to setup an EWS account.
You could setup the port after you setup the account initially, but in case you need this exact setting to go through the setup, if the setup assistant fails, you won’t be able to setup the account.