we are using Smartermail Enterprise Server 11.5 and we are facing the following error when trying to send eMails to one specific domain.
We tried sending mails to various different recipients from that domain but all came back with the same error content and we also tried to send from different sender Mail adresses
Von: System Administrator [mailto:System Administrator]
Gesendet: Montag, 12. Mai 2014 18:16
An: (our Mailadress)
Betreff: Delivery Failure
Could not deliver message to the following recipient(s):
Failed Recipient: (recipient Mailadress)
Reason: Remote host said: 451
-- The header and top 20 lines of the message follows --
Received: from MATD (UnknownHost [192.168.103.231]) by mail.schwabe.ch with
next comes the normal Mail Header Details and Mail Body Text.
In Smartermail Delivery Logsection i get the following Information:
18:15:30  Delivery for (our Mailadress) to (Recipient Mailadress) has completed (Bounced)
So far i assume that the recipient Mailserver bounces our mails and defines them as spam. Is there maybe any other way to investigate this issue from our Side
Kind regards for any reply and for help