If you want people to get your message, don't make it difficult for them
to find your message.
--
Paul Russell
Senior System Administrator
University of Notre Dame
On Mon, 27 Aug 2001 14:11:39 -0700, Dave Janecek <[log in to unmask]>
wrote:
><html>
><br>
><x-tab> </x-tab>Gi'day.<br>
><x-tab> </x-tab>Karen
>Reznek mentioned "bounced<br>
><x-tab> </x-tab>mail"
>in her note of Sat, 25 Aug 2001.<br>
><x-tab> </x-tab>Lemme
>share a recent quirk of ours.<br>
><br>
><x-tab> </x-tab>I use a
>commercial ISP, but our List <br>
><x-tab> </x-tab>is out of
>ASU. The two other ListOwners<br>
><x-tab> </x-tab>are
>located at ASU and the U of A.<br>
><br>
><x-tab> </x-tab>For about
>five weeks, I have been unable<br>
><x-tab> </x-tab>to
>communicate via my ISP to the U of A<br>
><x-tab> </x-tab>Owner, but
>I can communicate with ASU.<br>
><x-tab> </x-tab>Not only
>that, we: the ASU ListOwner<br>
><x-tab> </x-tab>and I
>received error messages about <br>
><x-tab> </x-tab>the U of A
>membership on our List. <br>
><br>
><x-tab> </x-tab>
>----- The following addresses had transient non-fatal errors -----<br>
><x-tab> </x-tab><[log in to unmask]
zona.edu><br>
><br>
> <x-tab> </x-tab>-----
>Transcript of session follows -----<br>
><x-tab> </x-tab><[log in to unmask]
zona.edu>...
>Deferred: Connection timed out with<br>
><x-tab> </x-tab>cosmo.as.ari
zona.edu.<br>
><x-tab> </x-tab>Warning:
>message still undelivered after 4 hours<br>
><x-tab> </x-tab>Will keep
>trying until message is 5 days old<br>
><br>
><x-tab> </x-tab>Not only
>that, eventually our ListOwner at the U of A was<br>
><x-tab> </x-tab>"un
>subscribed", by Listserve, for all the accrued messages <br>
><x-tab> </x-tab>not being
>delivered.<br>
><br>
><x-tab> </x-tab> I was
>forced to request assistance from my<br>
><x-tab> </x-tab>ISP
>Customer Service. Eventually the problem was resolved,<br>
><x-tab> </x-tab>here's the
>explanation.<br>
><br>
>"To Mail Administrator:<br>
><br>
>I am the Senior System Administrator for (My ISP) and I<br>
>wanted to bring to your attention a problem with your <@Y.com>
>mail<br>
>service.<br>
><br>
>I have recently upgraded our Linux mail server to the new 2.4.x
>stable<br>
>Linux kernel.<br>
><br>
>The new Linux Kernel implements Explicit Congestion Notification - a
>new<br>
>method defined in
>(<a href="http://www.ietf.org/rfc/rfc2481.txt?number=2481"
eudora="autourl"><font
color="#0000FF"><u>http://www.ietf.org/rfc/rfc2481.txt?number=2481</a></font
></u>)
>RFC<br>
>2481 for improving TCP performance in the presence of<br>
>network congestion by allowing routers to provide an early warning
>of<br>
>traffic flow problems.<br>
><br>
>Unfortunately, there are bugs in some Firewall products which cause
>them<br>
>to reject incoming packets with ECN enabled. I believe your company
>is<br>
>employing such a Firewall or packet filter on the public side of
>your<br>
>primary MX record (mta.Y.com), thus you are rejecting legitimate<br>
>mail service from many, many sources.<br>
><br>
>Currently in our small ISP environment (<10,000 email users) we
>have<br>
>queued over 40 messages destined for your mail server (mta.Y.com).<br>
>Below is a example of the mail Q listing -<br>
><br>
>##########################<br>
><br>
>f7OFBGL15955 2 Fri Aug 24 08:11
><<font color="#0000FF"><u>[log in to unmask]</font></u>><br>
>(Deferred: Connection refused by mta.Y.com.)<br>
><<font color="#0000FF"><u>[log in to unmask]</font></u>><br>
><br>
>###########################<br>
><br>
>As you can see, the SMTP connect is refused from the Y mail server.<br>
>This mail server is running the Linux 2.4.x Kernel with Explicit<br>
>Congestive Notification enabled.<br>
><br>
>Fixes are available from some router vendors, and have been since at
>least<br>
>mid-2000. These are not "feature patches" (which may add new
>features and<br>
>have new bugs), but purely bug fixes, and thus should be safe to use,
>even<br>
>for the most paranoid.<br>
><br>
>I will include some links with more relevant information for you to<br>
>review. I would be able to assist you in any fashion you would like
>for<br>
>testing purposes.<br>
><br>
>RELATED LINKS:<br>
><br>
>Linux Kenel FAQ (Anchored to appropriate section)<br>
><font color="#0000FF"><u><a href="http://www.tux.org/lkml/#s14-2"
eudora="autourl">http://www.tux.org/lkml/#s14-2<br>
><br>
></a></font></u>RFC 2481 (The official ECN Spec) <Please Obey><br>
><font color="#0000FF"><u><a
href="http://www.ietf.org/rfc/rfc2481.txt?number=2481"
eudora="autourl">http://www.ietf.org/rfc/rfc2481.txt?number=2481<br>
><br>
></a></font></u>Please let me know if it will be necessary for our ISP to
>disable ECN from<br>
>our 2.4.x kernel because of non RFC compliance on the part of the
>Excite<br>
>Network.<br>
><br>
>Thank you very much for your attention on this matter, I do
>appreciate<br>
>your time."<br>
><br>
><x-tab> </x-tab>Yes, the U
>of A HAD installed a new Firewall - unidentified<br>
><x-tab> </x-tab>manufacturer
>and version so far.<br>
><br>
><x-tab> </x-tab>I am now
>able to communicate via e-mail with my <br>
><x-tab> </x-tab>third
>ListOwner. We had been telephoning about the <br>
><x-tab> </x-tab>problem in
>the mean-time. Once the Firewall was<br>
><x-tab> </x-tab>corrected
>he received a flood of mail which had been <br>
><x-tab> </x-tab>building
>up outside the gate.<br>
><br>
><x-tab> </x-tab>Just
>something else to keep in mind when you <br>
><x-tab> </x-tab>receive
>"bounced" messages from Listmembers.<br>
><br>
><x-tab> </x-tab>Thank you
>for your time.<br>
><x-tab> </x-tab>Dave
>J.<br>
><br>
><br>
><x-tab> </x-tab><br>
><br>
> </html>
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