I am currently preparing a test dataset for a SharePoint WebPart to see how it scales on a customer SharePoint 2010 environment. The problem I faced here was that the environment is protected by Citrix Netscaler and every CSOM call was ended with a lovely exception. Problem 1: SSL The underlying connection was closed: Could not establish trust relationship for the SSL/TLS secure channel. The client uses https/SSL to secure the channel (good!