An app client can receive and display messages only in the following scenario when it is running in the background:
If your app content updates are not frequent, your app server can push background messages (with push-type set to 6). These messages operate discreetly, without the usual notifications, ringtones, or app badge number changes. If proxyData is set to ENABLE when you push such messages, Push Kit will write them to the database and your app process will not be started.