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>