Authenticated relay?

[Simon Barrett]

Hello,

How would I go about allowing a user to send using an email address from 
another domain after authenticating with his primary kolab email address via 
smtp auth?

We have a .ie domain name, our .com equivalent was bought through a separate 
provider.  A provision of that contract is mail aliasing; when set up, an 
email to user at example.com is sent to user at example.ie on our mail server.  
However, a particular user requires that he can reliably send using his 
address at is the .com domain.  He will be on the road mostly and will not 
have a static IP.

For the foreseeable future, only a handful of users will have this 
requirement, so implementing and administering a second domain instance is 
overkill.  However, I would like to have complete control over this relay and 
send and receive all company mail through our mail server.  I would also like 
to limit the functionality to the .com domain, if possible.

Currently, the error received is 554, Sender address rejected, Invalid sender.  
I'm using Kolab version 2.0.4.


Regards,

Simon Barrett