RFC 1861 (rfc1861) - Page 3 of 26
Simple Network Paging Protocol - Version 3 -Two-Way Enhanced
Alternative Format: Original Text Document
RFC 1861 SNPP - Version 3 October 1995
3. Why not just use Email and SMTP for paging?
Email, while quite reliable, is not always timely. A good example of
this is deferred messaging when a gateway is down. Suppose Mary Ghoti
() sends a message to Zaphod Beeblebrox's beeper
(). Hugecompany's gateway to the
Internet is down causing Mary's message to be deferred. Mary,
however, is not notified of this delay because her message has not
actually failed to reach its destination. Three hours later, the
link is restored, and (as soon as sendmail wakes up) the message is
sent. Obviously, if Mary's page concerned a meeting that was
supposed to happen 2 hours ago, there will be some minor
administrative details to work out between Mary and Zaphod!
On the other hand, if Mary had used her SNPP client (or simply
telnetted to the SNPP gateway), she would have immediately discovered
the network problem. She would have decided to invoke plan "B" and
call Zaphod's pager on the telephone, ringing him that way.
The obvious difference here is not page delivery, but the immediate
notification of a problem that affects your message. Standard email
and SMTP, while quite reliable in most cases, cannot be positively
guaranteed between all nodes at all times, making it less desirable
for emergency or urgent paging. This inability to guarantee delivery
could, whether rightly or wrongly, place the service provider in an
uncomfortable position with a client who has just received his or her
emergency page, six hours too late.
Another advantage of using a separate protocol for paging delivery is
that it gives the sender absolute flexibility over what is sent to
the pager. For instance, in the paging arena, where messages are
sent to alphanumeric pagers, it is less desirable to send the
recipient general header lines from a standard SMTP message. Much of
the information is useless, possibly redundant, and a waste of
precious RF bandwidth.
Therefore, when implementing an SMTP gateway, the service provider
should elect to parse out needed information (such as the sender, and
possibly subject) such to maximize the utility of the transmission.
Parsing generally means less control over content and format by the
message originator. SNPP provides a clean, effective way to send a
message, as written, to the recipient's pager.
The other consideration is the relative simplicity of the SNPP
protocol for manual telnet sessions versus someone trying to manually
hack a mail message into a gateway.
Gwinn Informational