William Herrin bill at
Sat Feb 20 16:36:37 UTC 2010

On Sat, Feb 20, 2010 at 8:08 AM, Rich Kulawiec <rsk at> wrote:
> 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]


Indeed, and the ones who are more than minimally competent have
considered the protocol as a whole and come to understand that at a
technical level the "reject don't bounce" theory has more holes in it
than you can shake a stick at. Find me a comprehensive solution and
I'll help you write the I-D but mere trash-talk about the people who
respect SMTP's architecture is unhelpful.

On Sat, Feb 20, 2010 at 10:06 AM,  <Valdis.Kletnieks at> wrote:
> 5321 Simple Mail Transfer Protocol. J. Klensin. October 2008. (Format:
>     TXT=225929 bytes) (Obsoletes RFC2821) (Updates RFC1123) (Status:
> It's been done already. It's been quoted in this thread even.
> There's no sense in Rick re-inventing the wheel when
> John Klensin and friends already
> fixed the flat and rebalanced it a year and a half ago.

They didn't exactly fix it. What they did is reinforce the importance
of generating a bounce message by keeping the existing "must" language
from 2821 but adding:

"A server MAY attempt to verify the return path before using its
address for delivery notifications"

Bill Herrin

William D. Herrin ................ herrin at  bill at
3005 Crane Dr. ...................... Web: <>
Falls Church, VA 22042-3004

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