Re: DNS or e-mail Problem ?

[Kevin Colby <kevinc grainsystems com>]

The offending setup is a combination of two lines:

> mail            IN      CNAME   server1
> @               IN      MX      5       mail

The MX record for your domain points to "mail", which
is itself a CNAME for "server1".  This is unacceptable.

I suggest the following:

> mail            IN      A               x.x.x.x     <<=== real ip
> @               IN      MX      5       mail

Then other mail servers may be willing to talk to you.

	- Kevin Colby
	  kevinc grainsystems com



Rene Groothuis wrote:
> 
> Hello Thomas,
> 
> Thank you for your suggestion, but I'm very familiar with the configuration
> of DNS (MX, CNAME etc).
> 
> In this mail I've included the zone file and maybe you can give me some more
> exact details what the problem is.
> 
> Extra information: my ISP is running the DNS service, in other words my ISP
> has put my domain name is there zone files.
> 
> ======== Zone file ===================
> @               IN      SOA     server1.mydomain.nl.    webmaster.mydomain.nl. (
>                         2000073001 ; serial
>                         86400 ; refresh
>                         3600 ; retry
>                         3600000 ; expire
>                         86400 ; default_ttl
>                         )
> www             IN      CNAME   server1
> ftp             IN      CNAME   server1
> smtp            IN      CNAME   server1
> pop3            IN      CNAME   server1
> telnet          IN      CNAME   server1
> mail            IN      CNAME   server1
> localhost               IN      A       127.0.0.1
> server1         IN      A       x.x.x.x     <<=== real ip address of mydomain
> local1          IN      A       192.168.1.1
> @               IN      MX      5       mail
> @               IN      NS      ns.mydomain.nl.
> 
> Thanks in advance.
> 
> Kind regards,
> Rene Groothuis
> 
> -----Original Message-----
> From: tma relay8 Austria EU net [mailto:tma relay8 Austria EU net]On
> Behalf Of Thomas Mandl
> Sent: maandag, juli 31, 2000 12:34
> To: Groothuis Collis nl
> Cc: redhat-install-list redhat com
> Subject: Re: DNS or e-mail Problem ?
> 
> Rene Groothuis wrote:
> >
> > Hello All,
> 
> Hi Rene,
> 
> > I have a problem and I don't know the solution for it. I want to send
> e-mail
> > from a windows machine which is connected to a Linux server and the Linux
> > server is connected to the internet. I get, have found to errors:
> >
> > >From the e-mail program:
> 
> I'm not sure about the cause of this error, but the return mail denotes,
> that the receiving mail host did not 'forward = relay' your message to
> the final receipient. Who delivered (or tried to deliver this message)?
> Do you run your own SMTP server on your Linux box?
> 
> > The message could not be sent because one of the reipients was rejected by
> > the server. The rejected email address:          nl Subject '......' etc
> etc
> > ....... Server Response '551 we do not relay', port: 25, Secure (SSL): No,
> > Server Error: 551, Error Number 0x800CCC79
> 
> This one points out that you have used a CNAME for your MX record in
> your DNS server zone configuration files. ***Never use CNAMES for MX or
> SOA records!!!*** Correct this and try sending your mail again. It is
> possible that this might correct your previous problem, since the
> receiving host will run the (E)HELO protocoll and does kind of a reverse
> MX lookup for the sending host (and if the MX record for the sending
> host is not correct or is a CNAME record) it will fail.
> 
> > And in de messages log file I see the following error:
> >
> > ..... named[3823]: sysquery: findns error (NXDOMAIN) on ns.mydomain.nl?
> > ..... named[3823]: "MYDOMAIN.NL IN MX" points to a CNAME
> (mail.mydomain.nl)
> >
> > Can somebody tell my why I get these kind or errors??
> >
> [...snip...]
> Hope this helps
> bye and best regards
> Thomas
> --
> Ing. Thomas Mandl, UNIX and IT-Security Consultant
> 
> e-mail  : Thomas Mandl EUnet at
> WWW     : http://members.EUnet.at/thomas.mandl (under construction!)
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> Phone   : +43 (0) 676/53 60 497 (Cellular Phone)
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