Re: DNS or e-mail Problem ?

[Thomas Mandl <thomas mandl EUnet at>]

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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