The email service Hey (from the makers of Basecamp) has a feature where the first time someone emails you it goes into a screening bucket. You can then approve those senders who are allowed to email you. If you don't approve, you don't see the emails anymore.

I initially signed up for the trail when the service launched. The first or second time I went to check the site/app it wasn't working. I was pretty much done with it at that point. I probably should have given it more of a chance and maybe they worked that out, but at $99/year for email my tolerance for issues is pretty low. They did (I suppose still do) have a lot of neat ideas around email though.