forwarding should use a selected mailserver

[Thorsten Schnebeck]

Hi,

I would like to solve a very special problem. Some Kolab-user forward their mail to an external exchange server. This external domain has 3 mails servers in its mx record with different metrics. Due to some very strange relay rules the the first and second attempt to forward a mail does time-out. Only the last server is the one that accepts incoming mails. There is no chance to change this messy setup. Its part of their fail-back strategy.
I would like to reduce the time for forwarding to this mail domain and drop sending according to mx metrics and want to send mails to anyuser at forwarddomain.net directly to the 3rd mailserver.
 
Question:
Is there  somewhere a magic postfix config where I can define the mailserver of a named mail domain?

Bye

  Thorsten