got the solution,
 
the Firewall in the network checks if the sender of the outgoing mailaddress is correct.
Per default the sender of notifications is otrs@<otrs_config_fQDN>
 
In my  case FQDN was not valid for sending outgoing mails.
 
After setting a valid Sender Email adress in Config.pm
   $Self->{NotificationSenderEmail} = 'otrs@blabla.com';
 
everything works fine
 
-----Ursprüngliche Nachricht-----
Von: otrs-bounces@otrs.org [mailto:otrs-bounces@otrs.org]Im Auftrag von Matthias Wegner
Gesendet: Donnerstag, 25. August 2005 11:20
An: otrs@otrs.org
Betreff: [otrs] Agent notifications are not sent

Hi there,

one of my otrs systems is not sending its agent notifications.
After receiving a message there is the following log entry
Sent agent 'NewTicket' notification to 'xxxxx'

xxxx ist the correct maildress.
But i dont get the notification Mail.

Sending an "AdminEmail" works fine.
Sending answeres and forwarding messages works fine.

Any ideas to this riddle ?

Matthias Wegner