Bill Jonas on Tue, 9 Oct 2001 15:13:08 -0400

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Re: [PLUG] post from NeoMail

On Tue, Oct 09, 2001 at 02:49:17PM -0400, wrote:
> What's up with this warning?
> X-Authentication-Warning: Host []
> claimed to be

It means that the host claimed to have a certain name and that the
receiving host didn't agree or otherwise couldn't substantiate the
claim.  In this case, couldn't do a reverse lookup

bj@neo:~$ host         A
bj@neo:~$ host
Nameserver not responding PTR record not found, try again  

The forward DNS is set up all right, but the receiving host does a
reverse lookup.  It's also why you see the "Received: from ([])" line.  It's also what it means when
you see "Received: from (
[])" -- the IP is in parentheses and brackets, the reverse
lookup is inside the parentheses, and who the sending host claimed to be
is outside and listed first.  It's why you might see, for example, spam
with a Received: header that starts out "from localhost.localdomain
( [w.x.y.z])"; claims to be localhost.localdomain.


Bill Jonas    *    *
"They that can give up  essential  liberty to obtain a little temporary
safety deserve neither liberty nor safety."        -- Benjamin Franklin
If encryption is outlawed, bayl bhgynjf jvyy unir raelcgvba.

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