How can I programmatically interact with hidden folders using EWS?

You can use the EWS Managed API or send SOAP XML messages to create, list, read, and delete hidden folders. The key steps involve creating a folder, setting its extended property `PidTagAttributeHidden` to `true` via `ExtendedPropertyDefinition`, and using `FolderTraversal.Deep` with a search filter to retrieve hidden folders. For detailed code examples, refer to the implementation sections of this article.