Ho do i setup fallback_transport in kolab postfix ??

Hi I have a situation here, I have configured kolab and everything is working fine.

 

My kolab postfix domain xyz.com now if I have to send a mail to user who is not in local user table but has email id xyz.com" title="mailto:userxyz.com">userxyz.com how do I do that.

In normal postfix all I have to do is setup

local_recipient_maps =

fallback_transport = xyz.com

 

the error in postfix logs are

 

“relay=kolabmailboxfilter, delay=0, status=bounced (service unavailable. Command output: Failed to set recipient: Invalid response code received from server, code 550 )R21;

 

 

this setup was working for me till I installed kolab

 

please help !!!

thanks in advance