[Dshield] SMTP Failure

George Theall theall at tifaware.com
Sun Jun 20 16:27:34 GMT 2004

On Sun, Jun 20, 2004 at 11:17:16AM -0400, Glenn Jarvis wrote:

> Router : DI-604
> ISP: Persona Communications
> Their email processor : Qmail
> 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.           
> 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. 

Ok, here's the deal.  Apparently your router will only let you get your
logs by sending them to you by email.  To accomplish this, it has some
type of a built-in mail server.  Like any mail server, it needs to speak
the protocol known as SMTP.  Unfortunately, your router's built-in mail
server doesn't quite follow the SMTP protocol since it appears to use
bare linefeeds in its messages rather than pairing them with carriage
returns as the SMTP protocol, as specified by RFC 2822 (aka 822bis),
requires.  [See section 2.3 of http://www.faqs.org/rfcs/rfc2822.html.]
Finally, qmail, the mail server used by your new ISP, rejects any
messages that don't adhere to the protocol completely, hence your
inability to send mail. 

I'd say the fault here lies mostly with Dlink since their built-in mail
server deviates from RFC 2822.  Still, part also lies IMO with qmail
since the general wisdom when implementing a protocol is to be strict in
what you send but liberal in what you accept. 

While you can try to argue the point with Dlink, I suspect they won't be
bothered to fix the issue.  And while your ISP could avoid the problem
by switching to a different mail server, I would be surprised if you
alone can provide sufficient motivation to make them switch.  Thus, you
may find only your alternatives are either to switch routers or to mail
your logs to another account, preferably one on a host that doesn't use

theall at tifaware.com
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