php – Multi-User Mailing Lists

Looking for a multi-user mailing list, where each admin has their own lists, templated, mailings, etc. Prefer open-source, PHP/MySqli. Similar to what MailChimp does; but skinnable (and sellable to list managers).

Features should allow one super-admin that manages everything. Then a new ‘instance’ that is managed by an admin-level person (the ‘list manager’. Each instance would manage their own lists, members, templates, mailings, etc.

The super-admin can modify the ‘skin’ of the software, sort of a white-label skinning.

I’ve looked into phpList and others, but they don’t seem to be built to allow a multi-list operation (separate admin areas).

Any ideas? Suggestions here are very old (5+ years). Have done some googles on this, but nothing stands out that has a multi-admin feature.