I actually ran a similar service maybe 10 years ago, as I wanted a way to find links I had tweeted. It just presented a web page of the links you have mentioned, it didn't send a newsletter.

Anyway my point is I also have a hard time (even now) believing people would pay for such a thing... Which is probably why none of my side projects have turned into a successful business ¯\_(ツ)_/¯