That is probably data being sent back to WD because one enabled the option to join the product improvement program. And the My Cloud does have the option to email the user under the Settings > Notifications > Notifications Email section.
There is a check box on the first screen one sees (with the OS 3 firmware) at first access of the Dashboard if I remember right to enable product improvement reporting. There is also the following under the “?” icon > Support section with an option to enable or disable:
Product Improvement Program
The Product Improvement Program collects and periodically sends diagnostic and usage information, which helps WD improve the quality and performance of our products. This information generally includes device, application and service usage, as well as error diagnostics. This may include items such as device configuration, CPU and other usage statistics by application, API calls, service crash information, network status, storage utilization, and size and type of files. •You will be helping drive future updates to our products
• It will enable our Support team to help you more efficiently
• You can stop participating at any time