The connection cannot be established.
“The response received from the service didn’t contain valid XML”
It seems that URL is used to web outlook. However, another URL is actually required here - URL of exchange web services.
I do not know exactly how to find it - I am not an exchange
administrator and know very little about it (I have not set it up even
once - we use an already configured one for Task Management
implementation). But I can explain how this URL can be found on our
exchange environment, so maybe the same action will lead to the correct
URL on the customer’s side.
This should be the link to MSExchangeServicesAppPool. So the base URL for that service will be based on URL for exchange synch. In our exchange this app is called EWS. It can be located by opening Webserver (IIS) in Server Manager. There in the tree under “Default Web Site” the EWS node is located. By opening advance settings, you will se that it is a virtual path. On our exchanage this app has “/EWS” virtual path. So, as the URL of our exchange machine is contoso.com, the base URL for the exchange synch will be: https://contoso.com/EWS. However, this is not all. On our exchange environment we should apply Exchange.asmx to that base URL, so the resulting URL will be https://contoso.com/EWS/Exchange.asmx. (You can actually see when the application of Exchange.asmx is not unreasonable, by looking if there is such a file - go to the Physical Path location found in Advance Settings of that MSExchangeServicesAppPool app, where we located the virtual path). If Exchange.asmx exists there, the it is a correct addition.
So maybe something like that is the necessary URL for them: https://bit-consulting.eu/EWS/Exchange.asmx