[cobalt-users] Mail loops back

[Klaus Schuster <hostmaster@xxxxxxxxxxxxx>]

For the past 3 days I tried to get rid of the following poblem :
(I call the domain *example.com*)

   ----- The following addresses had permanent fatal errors -----
<mwollner@xxxxxxxxxxx>

   ----- Transcript of session follows -----
554 5.0.0 MX list for example.com. points back to ns.example.com
554 5.3.5 <mwollner@xxxxxxxxxxx>... Local configuration error

Unfortunately this error belongs to all domains and all eMail accounts
on that XTR machine.

I would say this has something to do with the primary nameserver.
As soon as I remove ns.example.com I get the following error message :

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

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

I'm sure I'm overlooking something. But what ?
I feel like a greenhorn :-(

Who has a hint for me ? Thanks in advance !

Hostmaster ***