This is a third-party service cPanel integrated in order to manage mail lists. Similar to the above, a manual restart will most likely never be needed but WHM provides you with this option.
When on the page, you will be presented with a question “Are you sure you wish to restart this service?” In order to restart it, click the “Yes” button. This will take you to the changelog page, informing you that the service has been restarted.
