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Re: Paul's Mailfrom (Was: IETF SMTP Working GroupProposal at smtpng.org)
- From: Brad Knowles
- Date: Tue Aug 27 19:10:43 2002
At 12:16 PM +0200 2002/08/27, Bruce Campbell wrote:
Read my previous comment about mailing lists that do not change
the envelope sender (e.g., mailing lists that are instead run as
I understand the proposal to be based on the envelope sender, not the
sender in the body. Hence, mailing lists work, because they are the
envelope sender, not the person who submitted the mail to the mailing
Not if example.com is a vanity domain and is not allowed to
transmit mail directly to the outside world, or actively chooses to
use the relay services provided by their ISP. You may know the entry
point, but it can be difficult to determine all the possible exit
Pardon? Are you saying that for a given entity (say, example.com), your
administrative procedures are such that you do not know all the machines
that can send email directly to that part of the Internet outside that
I know. I set those machines up. They haven't really changed
much since I left in '97. But try listing 20 different names as MXes
for a mail-from label. Have you heard of this thing called "DNS
response truncation"? Do you know the kinds of problems it causes
for many MTAs, even today?
Even for an entity like aol.com, their outbound mail servers appear to be
a small(ish) set of circa 20 machines which can be listed appropriately by
It is if you have to know all the possible exit points for e-mail
that you may transmit.
Yes, entirely correct. However, the bulk of the Internet mail today is
from one host to another host. Knowledge of the path the mail takes, on
the SMTP level, is not needed by the mailer, unlike UUCP which required
the mailer to be aware of various routing topologies.
Indeed, it would be good to get this cleaned up. But let's be
realistic. When you have 256 total gTLDs and ccTLDs (plus the root
zone), served by 762 unique machines, and 413 of those machines are
open public/recursive nameservers in addition to their authoritative
duties, leaving everyone underneath 204 TLDs susceptible to attack
via cache poisoning at one or more servers for their TLD, you realize
that there are much more serious problems that have to be solved.
The rest of your mail is an invitation to clean up the little bit of
forward and reverse domain space that is under your immediate control,
which is a Good Thing IMO.
Brad Knowles, <firstname.lastname@example.org>
"They that can give up essential liberty to obtain a little temporary
safety deserve neither liberty nor safety."
-Benjamin Franklin, Historical Review of Pennsylvania.
GCS/IT d+(-) s:+(++)>: a C++(+++)$ UMBSHI++++$ P+>++ L+ !E W+++(--) N+ !w---
O- M++ V PS++(+++) PE- Y+(++) PGP>+++ t+(+++) 5++(+++) X++(+++) R+(+++)
tv+(+++) b+(++++) DI+(++++) D+(++) G+(++++) e++>++++ h--- r---(+++)* z(+++)