Re: [Exim] Example of legit email rejected by testing on rev…

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Autor: Leonardo Boselli
Fecha:  
A: James P. Roberts, exim-users, stunnel-users
Asunto: Re: [Exim] Example of legit email rejected by testing on reverse IP lookup
How does the thing works if you say in helo line the address on
reverse dns, that is:
h-64-105-159-234.PHLAPAFG.covad.net
since this have both a forward and a reverse address, it must work.
if even this try does not work, so it is broken the test on the other
end.

On 7 Dec 2002, at 21:54, James P. Roberts wrote:

> The following is the response from ipal.net to an ordinary email sent
> from punsterproductions.com (my own server); I include the headers
> from the message as well, for completeness. It was obviously rejected
> because the admin at mx0.ipal.net implemented a "reverse DNS" check,
> and the resulting hostname did not match. I've been making the point
> for some time that this is not a great idea, as one will block
> legitimate email, because there are so many people who are STUCK,
> without any recourse, with ISPs that refuse to properly delegate IP
> address blocks (they instead provide "dummy" host names for reverse
> lookups). My own so-called "business" DSL service (from Covad, the
> only DSL provider in my area) is such a case. Until I can afford a T1
> line from a "real" ISP, I am stuck with this situation. (Don't think
> I haven't tried to explain this to Covad. I might as well beat my
> head on a brick wall.)
>
> All I can do is ask MTA admins to not reject email just because the
> reverse DNS hostname doesn't match. In a lot of perfectly legitimate
> cases, it will not match. There are plenty of other (better) ways to
> block spam, without blocking legitimate email traffic.
>
> Jim Roberts
> Punster Productions, Inc.
>
>
> *** begin sample ***
>
> This message was created automatically by mail delivery software
> (Exim).
>
> A message that you sent could not be delivered to one or more of its
> recipients. This is a permanent error. The following address(es)
> failed:
>
>   phil-stunnel-users@???
>     SMTP error from remote mailer after RCPT
> TO:<phil-stunnel-users@???>:
>     host mx0.ipal.net [209.102.192.90]: 550
> <h-64-105-159-234.PHLAPAFG.covad.net[64.105.159.234]>:
>     Client host rejected: mail from domains with generic/dialup/DHCP
> addresses is not accepted - contact your ISP for support

>
> ------ This is a copy of the message, including all the headers.
> ------
>
> Return-path: <punster@???>
> Received: from [64.105.159.238] (helo=puns04)
> by puns01.punsterproductions.com with asmtp (TLSv1:RC4-MD5:128)
> (Exim 4.02)
> id 18KpIr-00076F-00; Sat, 07 Dec 2002 19:28:14 -0500
> Message-ID: <00ec01c29e50$b1f39c60$04fea8c0@localnet>
> Reply-To: "James P. Roberts" <punster@???>
> From: "James P. Roberts" <punster@???>
> To: "Phil Howard" <phil-stunnel-users@???>,
> <stunnel-users@???>
> References: <20021207012756.A1044@???>
> <Pine.LNX.4.33L2.0212062354250.9903-100000@???>
> <20021207025722.A2126@???>
> Subject: Re: POP/IMAP then STUNNEL->SMTP
> Date: Sat, 7 Dec 2002 19:28:10 -0500
> Organization: Punster Productions, Inc.
> MIME-Version: 1.0
> Content-Type: text/plain;
> charset="iso-8859-1"
> Content-Transfer-Encoding: 7bit
> X-Priority: 3
> X-MSMail-Priority: Normal
> X-Mailer: Microsoft Outlook Express 6.00.2800.1106
> X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2800.1106
>
> *** end sample ***
>
>
> --
>
> ## List details at http://www.exim.org/mailman/listinfo/exim-users
> ## Exim details at http://www.exim.org/ ##
>



--
Leonardo Boselli
Nucleo Informatico e Telematico del Dipartimento Ingegneria Civile
Universita` di Firenze , V. S. Marta 3 - I-50139 Firenze
tel +39 0554796431 cell +39 3488605348 fax +39 055495333
http://www.dicea.unifi.it/~leo