Currently there is no convenient way to get a list for each of your domains what sending IP address(es) are assigned to them, the only way is using the website drill down into each individual domain's details.

Exposing the IP Address(es) of each domain in the /domains API endpoint seems like a good solution.

Additionally being able in the website to enter a sending IP address on the domains listing page and it would show all the domains with that sending IP address assigned.