Enabling open tracking on an entire server has become easier with the launch of Postmark's new feature, allowing users to automatically track opens in HTML emails sent through a specific server with just one click. This can be achieved by using either the account management endpoint or the server-specific endpoint via API calls, and will update all HTML emails sent through that server to have their opens tracked. To implement this feature, users need to set TrackOpens to true for the specific server in the API call, which responds with updated server settings. Once enabled, open tracking can be disabled for individual messages by setting TrackOpens to false.