Which distinction won't users make? Between the system sending an email and the poster sending an email? Or between "notify me of new search results" in a search engine like Google, and "notify me of new search results" in the context of Dreamwidth? Either way I think it comes down to how it's presented; but I'm not sure there's much point going further with that, because it certainly won't work if there isn't the will to make it work, and I think it's clear that will isn't here.