&gt; You can send an email(messaging) behind the scene<p>So... how Coinbase handles it, what is the format? Coinkite? Copay? The nth popular wallet? You can easily see that you need a standarization, it doesn&#x27;t matter if its by email, morse, or slack.<p>Now, Sig3 is the name of a service, with Sig3 you can use any n-m wallet.