Tanstaafl wrote:
On 10/14/2014 1:58 PM, Miles Fidelman <mfidelman@meetinghouse.net> wrote:Well, this really is OT for debian-users, but.... Turns out that SMTP WAS/IS intended to be reliable.Reliable, absolutely. 100% reliable? That simply isn't possible when people are involved in the equation (people mis-configure servers - whether accidentally, through ignorance, or intentionally (just because that is the way they want it).I'd always lumped SMTP in the category of unreliable protocols, w/o guaranteed deliveryThe protocol itself is extremely reliable. It is what people *do* with it that can cause it to become less reliable/resilient.
There is a technical distinction between "best efforts" (unreliable) protocols, such as IP ('fire and forget' if you will), and "reliable" protocols, such as TCP (with explicit acks and retransmits).
At least in the technical circles I run in (BBN - you know, we built the ARPANET; Ray Tomlinson, who coined use of the @ sign in email nominally worked for me, for a short period - in a matrixy version of "worked for"), SMTP is usually discussed as providing a "best efforts" (unreliable) service -- which, in reality, it is (particularly in real world configurations where mail often gets relayed through multiple servers).
So.. I was just a bit surprised to go back and read the RFC and discover that SMTP is explicitly intended to provide a reliable service.
As to "100% reliable" - nothing is 100% reliable. Miles Fidelman -- In theory, there is no difference between theory and practice. In practice, there is. .... Yogi Berra