[cobalt-users] Mail only sub-domain

["Neil Stringer" <neil@xxxxxxxxxxxxxxx>]

Hi All
Please excuse me if this exists in the archive -  I have looked, but
have not seen a definitive answer...

I have a domain, say mydomain.com

I need sub domains to be able to receive email on mydomain.com and
mydept.mydomain.com (and mydept2.mydomain.com etc). I do not need the
sub domain for any other purpose, now web, no ftp, no telnet, no
nothing, just mail.

I have created an A record to resolve mail.mydomain.com
I created an MX record to refer mydomain.com to mail.mydomain.com 
and an MX record to refer mydept.mydomain.com to mail.mydomain.com, 

When I send mail to recipient@xxxxxxxxxxxxxxxxxxx I get the following
warning

   ----- The following addresses had permanent fatal errors -----
<recipient@xxxxxxxxxxxxxxxxxxx>
    (reason: system config error)

   ----- Transcript of session follows -----
553 5.3.5 mail.mydomain.com. config error: mail loops back to me (MX
problem?) 554 5.3.5 <recipient@xxxxxxxxxxxxxxxxxxx>... Local
configuration error

The contents of the relevant file in /etc/named are 

$TTL 86400
mydomain.com. IN SOA ns1.mydomain.com. myname.mydomain.com. (
        2003030309
        10800
        3600
        604800
        86400
        )
mydomain.com.        IN      NS      ns1.mydomain.com.
mydomain.com.        IN      NS      ns2.mydomain.com.
; End SOA Header
;
; Do Not edit BIND db files directly.
; Use the administrative web user interface
; /admin/ -> Control Panel -> DNS Parameters
; Custom additions may be made by creating a file of the same name as
this but ; with a; .include suffix.  Click Save Changes in the DNS web
interface and ; the inclusion will be made. ;
mydomain.com.          in      a       1.1.1.1
ftp.mydomain.com.      in      a       1.1.1.1
mydept.mydomain.com.   in      a       1.1.1.1
mail.mydomain.com.     in      a       1.1.1.1
ns1.mydomain.com.      in      a       1.1.1.1
ns2.mydomain.com.      in      a       1.1.1.2
www.mydomain.com.      in      a       1.1.1.1
mydomain.com.          in      mx      30 mail.mydomain.com.
mydept                 in      mx      30 mail.mydomain.com.

Can anyone please advise on what I am doing wrong, and how to correct
it.
--
Many thanks
Neil