If the owner of ccrg.com wants ksmith to receive email addressed to ksmith@ccrg.org they first have to find out what ksmith's email address is. Let's say ksmith's email address is ksmith@xyg.org.
Using the change domain email forwarding interface the owner of ccrg.com can specify ksmith in the "route from" box and specify ksmith@xyg.org in the "route to" box. This means that email addressed to ksmith@ccrg.org will be delivered to ksmith@xyg.org.
You can only add two new addresses at one time. If you want to add more than that, then add two and submit the changes. Repeat until done.
This interface can also be used to simply delete a forwarding instruction provided earlier. If email addressed to don@ccrg.org is currently being delivered to don@idiom.com and the owner of ccrg.org wants to end this arrangement, they can do so with a click in the delete box next to the forwarding instruction followed by a submitting the change.
Mail can be forwarded to multiple people at the same time. Separate the recipients with a comma and a space.