All RSSMicro internal feeds are PubSubHubBub enabled, subscribers can take advantage of RSSMicro hub and receive RSSMicro feed updates in real-time. Checking the server logs we have noticed a relatively new PubSubHubBub subscription service started at
https://pshb-service.appspot.com/ we couldn't find any information on the web regarding the nature or the source of this new service, however we have all the reasons to believe that this is in fact Google subscription service to PubSubHubBub enabled feeds. The service has implemented HTTPS protocol using Hub.secret parameter for secure server to server connection.
RSSMicro hub has been able to verify all the secure subscription requests coming from the source and pushing content to the subscriber's address above.
I will update this post once I find more information about this particular subscriber.