[Dshield] SMTP Failure

Meidinger Chris chris.meidinger at badenit.de
Sun Jun 20 16:18:01 GMT 2004

 Hi Glenn,

I can imagine your frustration. If I was in your situation, I would use a
packet sniffer (such as ethereal from www.ethereal.com) between the router
and the mail server to capture that traffic, then capture a session from
your PC to the mail server. Comparing these traffic flows may provide a

It is possible that your ISP is filtering based on SMTP behavior to avoid
spam; I am not intimately familiar with qmail, but in postfix for example,
on can easily demand properly spoken SMTP. Many spambots don't speak proper
SMTP, and so this is intended to kick their mails out. Perhaps your router
is skipping a command, or something of that nature. 

The only real way to analyze it, would be to insert a packet sniffer between
router and server, and see exactly what happens. 
If you need help doing this, feel free to contact me directly,


Chris Meidinger

> -----Original Message-----
> From: list-bounces at lists.dshield.org 
> [mailto:list-bounces at lists.dshield.org] On Behalf Of Glenn Jarvis
> Sent: Sunday, June 20, 2004 5:17 PM
> To: list at lists.dshield.org
> Subject: [Dshield] SMTP Failure
> Dear List,
> Forgive the intrusion, but I haven't been able to find the 
> source of the problem. It's my hope, that with all the 
> experienced folks here that someone can offer me the source 
> of the problem. So far, I keep getting sent back and forth 
> for the last few weeks or so, between my ISP and DLink 
> Canada. I'm basically at my wits end (and almost bald).
> System Information
> --------------------
> P3 (600Mhz)
> 256MB ram
> Win98SE
> Internet Connection : cable (SuperLink2800 modem) Router : DI-604
> ISP: Persona Communications
> Their email processor : Qmail
> I used to be with Bell Sympatico using DSL access , however 
> the phone lines in the town I live in a pretty bad, so cable 
> was a better solution. With the DSL, I had no problems 
> getting my logs from the router. There is only one option, 
> and that is via email. Since I have been hooked up with 
> cable, I can no longer receive them. The settings were 
> verified as correct within the router, as well as my network 
> properties.I can send / receive email as you can see here. 
> The router gives you an option to send the log manually via 
> email, which I have tried. However, even if manual or 
> automatic, this is what I see in the log of the router...
> Jun/20/2004 11:00:59     SMTP: sending mail fail           
> Jun/20/2004 11:00:59     SMTP: unexpected reply: 451 See 
> http://pobox.com/~djb/docs/smtplf.html.           
> Jun/20/2004 11:00:59     SMTP: unexpected reply: 451 See 
> http://pobox.com/~djb/docs/smtplf.html.           
> Jun/20/2004 11:00:58     SMTP: unexpected reply: 451 See 
> http://pobox.com/~djb/docs/smtplf.html.           
> Jun/20/2004 11:00:56     Sending one E-mail            Subject: Manual
> I'm definately not as experienced as you folks here, but even 
> after I looked up the link, I still have no idea what it 
> means to me, the end user. I know Sympatico uses InterMail 
> for their email processing. I've tried asking DLink Canada 
> (and I have the lastest firmware), but their only reply is 
> that it's my ISP's mailserver. That was all they stated each 
> time. Now my ISP has been trying to figure this out all this time. 
> This is their statement...
> <>I have sent the information to our administrator for his 
> review.  He has replied to me concluding that there is 
> nothing we can do, that the issue is with the router not 
> using the standard mail protocol, explaining why your PC can 
> send but the router can not.  He suggested that you contact 
> the manufacturer, which I know you have already done, to 
> advise them of the issue.
> I am sorry that we where not able to resolve the issue, but I 
> am confident that we have exhausted every avenue to correct it.
> I'm at my wits end here now. I've tried asking about this on 
> different forums and such and nobody there seems to know why 
> this is happening. 
> The offer a possible solution and that is to setup my own 
> local mailserver. I'm not sure if that would help or not 
> (although it would be a learning curve for me). Plus, since 
> I'm not experienced at setting up one of these things, the 
> last thing I want to do is have a insecure mailserver, so 
> much reading is in order. Additionally, I'm not sure if 
> setting up my own mailserver would work since no one really 
> knows why this is happening.
> I've tried different email clients,different browsers, 
> uninstalling my TCP/IP, and then reinstalling. I've tried 
> opening port 25 to the ISP's mailserver IP address as well. 
> All with the same result as above.
> Thanks for your patience of this intrusion as it really isn't 
> "ontopic", and your suggestions.
> Glenn
> --
> Reclaim Your Inbox!
> http://www.mozilla.org/products/thunderbird
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