Paul Vixie vixie at
Sun Feb 21 14:57:31 UTC 2010

Rich Kulawiec <rsk at> writes:

> On Fri, Feb 19, 2010 at 08:20:36PM -0500, William Herrin wrote:
>> Whine all you want about backscatter but until you propose a
>> comprehensive solution that's still reasonably compatible with RFC
>> 2821's section 3.7 you're just talking trash.
> We're well past that.  Every minimally-competent postmaster on this
> planet knows that clause became operationally obsolete years ago [1], and
> has configured their mail systems to always reject, never bounce. [2]

for smtp, i agree.  yet, uucp and other non-smtp last miles are not dead.

> [2] Yes, there are occasionally some edge cases of limited scope and
> duration that can be tough to handle.  ...  The key points here are
> "limited scope" and "limited duration".  There is never any reason or
> need in any mail environment to permit these problems to grow beyond
> those boundaries.

so, a uucp-only site should have upgraded to real smtp by now, and by not
doing it they and their internet gateway are a joint menace to society?

that seems overly harsh.  there was a time (1986 or so?) when most of the
MX RR's in DNS were smtp gateways for uucp-connected (or decnet-connected,
etc) nodes.  it was never possible to reject nonexistent at uucpconnected at
their gateway since the gateway didn't know what existed or not.  i'm not
ready to declare that era dead.

william herrin had a pretty good list of suggested tests to avoid sending
useless bounce messages:

	No bounce if the message claimed to be from a mailing list.
	No bounce if the spam scored higher than 8 in spamassassin
	No bounce if the server which you received the spam from doesn't match
	my domain's published SPF records evaluated as if "~all" and "?all"
		are "-all"

i think if RFC 2821 is to be updated to address the backscatter problem, it
ought to be along those lines, rather than "everything must be synchronous."
Paul Vixie

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