Add the following code that appears in bold - solved my problem:
BasicHttpBinding binding = new BasicHttpBinding();
binding.Security.Mode = BasicHttpSecurityMode.Transport;
binding.Security.Transport.ClientCredentialType = HttpClientCredentialType.Windows;
binding.MaxReceivedMessageSize = 50000000;
binding.ReaderQuotas.MaxArrayLength = 50000000;
binding.ReaderQuotas.MaxStringContentLength = 50000000;
binding.ReaderQuotas.MaxNameTableCharCount = 50000000;
EndpointAddress endpoint = new EndpointAddress(new Uri("https://server/EWS/Exchange.asmx"));
ExchangeServicePortTypeClient ews = new ExchangeServicePortTypeClient(binding, endpoint);
Kind regards,