On 8/11/2010 9:53 AM, Murray S. Kucherawy wrote:
From: owner-ietf-smtp(_at_)mail(_dot_)imc(_dot_)org [mailto:owner-ietf-
smtp(_at_)mail(_dot_)imc(_dot_)org] On Behalf Of John C Klensin
Sent: Wednesday, August 11, 2010 8:15 AM
To: dcrocker(_at_)bbiw(_dot_)net; SMTP Interest Group
Subject: Re: Changing RFC 5322 guidance about crlf.crlf response delay
I note, again fwiw, that I've been trying to get various
advocates for a ban (or near-ban) on NDNs to write that separate
document and propose a specific model at regular intervals since
well before 2821 was completed.
I'm new to that particular topic. Can you explain its motivation or point me
to a discussion thread that lays it out so I can get some context?
"Long delays after the<CRLF>.<CRLF> is received can
result in timeouts and duplicate messages. Deferring
detailed message analysis until after the SMTP
connection has closed can result in non-delivery
notifications, possibly sent to incorrect addresses. A
receiver-SMTP MUST carefully balance these two
considerations, i.e., the time required to respond to
the final<CRLF>.<CRLF> end of data indicator and the
desirable goal of rejecting undeliverable or
unacceptable messages at SMTP time."
I like this text. I think it reflects current operational realities quite
Although we can't offer a precise algorithm, because we don't know enough and
because network variances make this problematic to do at all, the draft text
doesn't provide any assistance beyond "thar be dragons". At the least, we
should try to offer tradeoffs, factors, and may even (sudder) a heuristic.
For example, a delay time of up to 2 seconds is probably pretty safe.