I have the same problem from a Linux/sendmail server that I run behind a NAT router. The NAT router is currently Eigerstein2beta but I used to have the same problem under other NAT routers.
I can dig out the failure messages but they all hint at the reverse domain not checking out to the satisfaction of the recipient mail server. The recipient domains that reliably bounce mail are: aol.com oracle.com talk21.com There are probably others - these are just the ones I remember. I suspect at least part of the problem is to do with my DNS configuration because the extent of the problem varies with the manner in which the email is generated. I use Perl to write a lot of automated response emails and those sent by Perl's MIME::Lite module produce such a bounce far more often than those sent by Perl's Net::SMTP module. Barbara, a search of the web used to turn up a few people who were having this problem (on BSD mail servers IIRC) but I never found solutions to their problems. I didn't know Mark's tip about HELO <myname> so I will try that (when I get a minute) and report back. Lee ----- Original Message ----- From: "Mark Plowman" <[EMAIL PROTECTED]> To: <[EMAIL PROTECTED]> Cc: <[EMAIL PROTECTED]> Sent: Tuesday, November 13, 2001 7:34 AM Subject: Re: [Leaf-user] Exchange server behind EigerStein s/NAT can not send to some site s > Barbara, > > > From: Barbara Miller <[EMAIL PROTECTED]> > > Date: Tue, 13 Nov 2001 15:58:49 +0100 > > > > Hello, > > > > I'm running a small PC network, including an Exchange server, behind > > an EigerStein using NAT. Most of the time everything works great. > > We are doing the same, but using Postfix (which I can recommend) under > Linux. > > I also follow the Postfix mailing list and have learnt a *lot* about > mail servers there... > > > > However, e-mail sent by the Exchange server to a few domains fails, > > I understand, because there is no public reverse DNS for the > > Exchange server, and some mail servers therefore suspect e-mail > > coming from it is spam. Only the EigerStein router has a public IP. > > If mail is being rejected by a domain, send a mail to the > [EMAIL PROTECTED] and ask him/her what you are doing wrong. > Perhaps the failure notification from the remote server gives you a > few clues. Be careful, I understand that Exchange "helpfully" > massages the messages and alters the content, this may be a pain... > > Perhaps you could post one of the bounce messages so that we could > study it? > > > > In other words, e-mail from the Exchange server includes headers like > > this... > > > > Received: from server.aac.edu (gw.aac.edu [195.113.149.145]) > > by ... > > > > ... where server.aac.edu is the Exchange server, which has no external DNS > > entry, and gw.aac.edu is the NATing EigerStein router with public IP > > 195.113.149.145. > > I think that it unlikely that *that* is the problem. > > Mail servers rarely look at "received" lines. > > Things they do look at include: > > 1) The name your server gives when it says "HELO <myname>" or "EHLO > <myname>". > > <Myname> should be the fully qualified DNS name of your server and > some people check this (i.e. do a lookup of the name and see if > matches the IP of your LEAF). > > Having said that, our server name (duif.hexapole.nl) doesn't > resolve and I have never knowingly lost an email. The MX for > hexapole.nl does resolve to the IP of our LEAF, so that *is* good. > > 2) More things that escape me at the moment ;-) > > > > What do I need to do to make this failing e-mail go through? > > More information. > > The "bounce" message, info from the remote postmaster > > > > Add DNS entries for server.aac.edu? Can I rename the Exchange > > Server "gw" (since there's no gw.aac.edu on the internal network)? > > Niether would do any harm and could well do some good. Try it! > > > > Thanks for your attention! > > > > Barbara Miller > > > Greetings > > Mark Plowman > > _______________________________________________ > Leaf-user mailing list > [EMAIL PROTECTED] > https://lists.sourceforge.net/lists/listinfo/leaf-user > _______________________________________________ Leaf-user mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/leaf-user
