switching between two domains' inboxes -- how to?

switching between two domains' inboxes -- how to?

I've just set up my second domain (as I've just registered a new company). Both domains exist under my original Zoho account. I want to keep the two domains inboxes separate from each other, but be able to easily swop viewing from one to the other. I can't see how to be logged into domain 1, but able to click anywhere to switch over to domain 2. Am I missing something obvious?