You are either from Mars or some other planet when you can keep saying that email server providers are decentralized... they are not decentralized.
Do you know that few days ago when fastly servers went down half of the internet went down including reddit, amazon, paypal, amazon, ebay, vimeo, etc.
If you know that huge majority of people use gmail and google services you can't really call anything like that decentralized.
There is one research showing that over 75% of all Gmail users are connected with their mobile devices...so much about decentralization.

PS
You are still avoiding to answer my question to explain how your mobile nodes are actually working.