Nice! What I've done is pretty basic, I took the default write policy example at https://github.com/hoytech/strfry/blob/master/docs/plugins.md, flipped it so that it's a blacklist rather than a whitelist, and added the ability to exclude notes that contain certain words or phrases.

I'm sure I'll have to evolve it as spam happens, but for the moment it should be enough to capture those annoying crypto spambots that plague this place.