This deserves 4.5 stars, because it really "does what it says on the tin" to use a British expression.

That said, there are two areas that could be improved:
• Import/Export. The docs make it seem easy, but after you do export you find that each entry has a unique ID. How an import handles a collision of example.com whitelist with an existing entry of example.com greylist is "left as an exercise for the reader" as you can find in a textbook after a puzzling new idea is presented.
• Better granularity with subdomains, etc.

The dev does work on this project, so these overly wordy concerns may well be resolved - perhaps soon.