Your message leaves me confused.
In terms of simplicity: SNPP is no less complicated than SMTP. Further,
in terms of clients, there are dozens of different SMTP clients, all of
which hide the protocol from the user.
In terms of store-and-forward: if you think paging networks are
reliable, you probably haven't used one recently. In the SF area, pages
take on the average of 5 minutes to be delivered, and one out of every
three of my pages gets dropped. Because paging networks are simplex,
there is simply no way to ensure reliable behavior. The best you can do
is report that IXO said it accepted the page. Beyond that, anything
else is a fiction.
So, I think we are back to: why do we need another protocol (and
associated infrastructure), when we already have a widespread SMTP
infrastructure...
/mtr