Re: Need volunteer to draft definition of reliable messaging,wasRE:reliable messaging - hop by hop

[Dan Weinreb <dlw@exceloncorp.com>]

   Date: Mon, 03 Sep 2001 21:01:49 -0400
   From: Martin W Sachs <mwsachs@us.ibm.com>

   MWS2:  If the partition happens between the time the To party MSH
   reads the message and the time it sends the ACK, for a single hop,
   the To MSH will know that it couldn't send the ACK and (hopefully)
   retry later.  

Actually, that brings up an important question about our failure
model.  In a single-hop scenario, if the communication protocol is
HTTP, the sender does know that it can't send.

But in the case of using Email (SMTP) as a communication protocol, the
communication layer can *itself* be multi-hop (using store-and-foward,
a.k.a. "indirect", routing, perhaps directed by MX records from the
DNS, etc), and so it may not be clear to the sender whether the
message could or could not be sent.