according to this link https://wiki.mozilla.org/WebAPI/SimplePush/Protocol#AppServer_-.3E_PushServer

when the ups sends the "notification" PUT request to the simplePush server( in this case Mozilla's ) the header should be a 'Content-Type': 'x-form-....'

Currently it looks like this:https://github.com/aerogear/aerogear-unifiedpush-server/blob/master/server/src/main/java/org/jboss/aerogear/unifiedpush/message/sender/SimplePushNotificationSender.java#L90

'Accept': 'x-form...'

using sebi's chuckpush app, https://github.com/lholmquist/chuckpush,i am unable to get a notification using the UPS until i change that header. or use the node simple-push sender, https://github.com/lholmquist/aerogear-simplepush-node-sender-client

I haven't tried our SImplePush implementation yet