550 not local host not a gateway

[SANWalla]

Hallo zusammen.
ich bekomme wenn ich an eine bestimmte Adresse sende folgende
Fehlermeldung "550 not local host scherpenberg.de, not a gateway"
An anderen Adressen z.B.: xxx@gmx.de kann ich senden.
Kann mir einer sagen was 550 bedeutet ??

Über eine Info bin ich euch dankbar.

[m3]

5.X.X   Permanent Failure

       A permanent failure is one which is not likely to be resolved by
       resending the message in the current form.  Some change to the
       message or the destination must be made for successful delivery.


X.5.X   Mail Delivery Protocol Status

          The mail delivery protocol status codes report failures
          involving the message delivery protocol.  These failures
          include the full range of problems resulting from
          implementation errors or an unreliable connection.  Mail
          delivery protocol issues may be controlled by many parties
          including the originating system, destination system, or
          intermediate system administrators.

X.5.0   Other or undefined protocol status

          Something was wrong with the protocol necessary to deliver
          the message to the next hop and the problem cannot be well
          expressed with any of the other provided detail codes.

http://www.faqs.org/rfcs/rfc1893.html

Klingt nach einem dns oder routing-Problem.