Using DNS a Domino administrator could create an entry in the Domino Directory for a special user called "helpdesk". Then the admin would specify the recipient's address in the "Forwarding address" field of the recipient's "Person document". The forwarding address would be helpdesk@k1000.company.com

There would also need to be routing instructions to deliver to K1000.yourcompany.com  Very Simply the host K1000.yourcompany.com must be resolvable by the DNS server that your Domino server uses.  A simple test would be, can you correctly ping that name from your Domino Server?

From Domino's perspective, it is the same as delivering mail to the internet but logically what happens is it gets delivered to your local K1000 appliance. 

In this way, even external users can send mail to the K1000 appliance because they still address their mail to your regular company.com address.  Any mail that comes from the k1000 appliance can be set to appear to be coming from helpdesk@yourcompany.com by puttting this value (ie helpdesk@yourcompany.com) in the Alt. email address field for your helpdesk queue.  

The prefix of the "Alt. email address" (ie helpdesk) must match the prefix of the special users' email address (ie helpdesk@yourcompany.com)