Subject: Re: Sendmail and anti-spam
To: None <>
From: William O Ferry <>
List: tech-userlevel
Date: 02/18/1999 08:19:35
In, you wrote:
>On Wed, Feb 17, 1999 at 09:17:33PM -0800, Michael Graff wrote:
>> Perhaps he means "valid return envelopes"
>Yeah. Or the no DNS entry thing from Claus Assmans anti-spam rules:
># no DNS entry? this is dangerous!
>R$*<@$*$~P>$*  $#error $@ 4.1.8 $: 418 unresolvable host name $2$3, check your
>  configuration.  

     I am not sure if this is the same thing I was running into, but please if
you are going to consider adding such a rule try to make sure you're not
blocking email from innocent users as well.  I have found that there is one
site (can't remember which) that simply *refuses* to accept email from my
domain, on the grounds that my host IP addresses do not have valid hostnames.
In fact they have no hostnames at all, this is something I have been fighting
with my ISP for 3 months to do something about (a few FTP sites have refused
connections on the same grounds), I believe they finally got around to fixing
it 2 days ago.

     But my mail programs were sticking a valid email address at the top,
from a different domain, yet this mail server still refused to accept my

     So please consider that IP addresses may not have hostnames just because
it is a non-trivial thing to do (trivial for the ISP yes, but for the end user
it is nearly impossible).  To deny service from people over something that is
completely out of their control seems totally unfair to me, and to be honest
downright stupid.  I have also seen several ISPs (and I haven't looked at many)
that do not put hostnames on their modem pool IPs, I believe this site's email
server would categorically deny any email from people dialing in from these
ISPs as well.  Just look at your http logs (if you have reverse DNS on) and
notice just how many IP addresses do not have hostnames for them.  At least on
my site it's a rather large number, certainly not an uncommon occurrance...

     To be fair however, I am probably coming from the opposite view of things.
I personally don't understand this anti-spam stuff at all.  I have always taken
the "innocent until proven guilty" stance, I do not want to risk executing an
innocent email just because it COULD be guilty of being spam.  =)  *I'll* be
the one to decide whether or not I want to read my email, not my computer, with
rules set arbitrarily by somebody I don't even know.  Sounds like what I read
about Outlook throwing out the e-cards from Blue Mountain.  Not trying to
start any kind of war here, just pointing out where I am coming from.

     But *please* don't have the default setup throw out email on a condition
that a site admin cannot do anything about.

                                                          Will Ferry