On Thu, 2003-05-29 at 08:41, Pierre Fortin wrote: > On Mon, 26 May 2003 09:22:28 -0300 (BRT) Alan Wilter Sousa da Silva > <[EMAIL PROTECTED]> wrote: > > > How can I verify if I have a misconfigured DNS? > > I mean, how can I know that I won't have e-mail reject for a such > > mechanism suggest by Pierre? > > Looking at your post's headers... > > > Received: from iracema.biof.ufrj.br (iracema.biof.ufrj.br > > [146.164.76.162]) > 1:^^^^^^^^^^^^^^^^^^^^ > 2:^^^^^^^^^^^^^^^^^^^^ > > by chagas.biof.ufrj.br (8.12.9/8.12.9) with ESMTP id > > h4QCQ8kh009901 for <[EMAIL PROTECTED]>; Mon, 26 May 2003 > > 09:26:08 -0300 > > This initial header shows that your server claimed to be 1 and rDNS got 2 > from your IP address... so both pieces match which is good. > > Conversely, the same initial Received header for missing rDNS should look > like this: > > Received: from iracema.biof.ufrj.br (unknown [146.164.76.162]) > > If 1 and 2 don't match, then my mailer also tries to resolve 1 (the name > you configured in your mailer). In this case, both must pass the test... > > Moral of the story: make sure your rDNS is correct and your mailer sends a > known-to-DNS name in the HELO/EHLO packet, or your mail may be rejected... > > HTH >
Additionally, be aware that this is a religious issue. On the one hand, rejecting mail from servers that don't rDNS to the name presented in HELO/EHLO is kosher and may even reduce spam by a bit. On the other hand, it prevents one from receiving mail from the very large number of legitimate servers hosted on networks where the mail admin has no control over rDNS. At the end of the day, admins need to balance the value of this anti-spam measure versus the value of being able to transfer mail with non-commercial entities on the Internet. I don't insist on rDNS matching because I would have to reject all of my own mail :-) I operate three mail servers and cannot control rDNS for any of them. About once every six months I get a reject, usually with an incoherent "we don't like spam" message attached, from some one who's enabled rDNS matching without realizing the consequences. Since these messages are usually asking for help that I'm trying to send to them, I'd say the loss of communication is a bigger loss to them than it is to me. -- Jack Coates Monkeynoodle: A Scientific Venture... http://www.monkeynoodle.org/resume.html
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