Trouble Importing a Vpopmail Domain

I am testing Virtualmin GPL on our webserver host and decided that part of my test would be importing an existing domain. We use vpopmail, which when adding new domains is working as expected. This domain is email only at the moment. When I go to the import frame in Virtualmin, there are choices regarding how to detect email domains. None make sense with vpopmail based domains. Is there a way to import a vpopmail domain? Thanks much.