A common occurrence these days of rapid acquisitions is where an organization using Notes/Domino acquires a company that's using Outlook/Exchange, and until the infrastructure is replaced with notes/Domino for all the users, there's a need to exchange emails between the 2 groups. This requires some changes to the Domino setup.
A nice step-by-step article for doing this is published by my colleague recently. I would recommend this for everyone or bookmark it for future reference.
Do add comments on the WIKI directly if you have suggestions.