I created a similar service earlier this year which runs on exactly the same idea (forwarding emails to unsubscribe to them). It's nice to see some validation for the idea on HN.

I've attacked the problem from a different angle though - I've tried to automate the service a lot more. Automatically looking for the unsubscribe button and filling out any HTML forms that appear etc. It doesn't always work but it's been fun trying to work out ways to automate the different steps etc.

If anyone is interested in a similar product with a slightly different way of doing things, different pricing and a web UI, please check out: https://www.stopthat.email/

Hopefully you don't mind the health competition ryanmjacobs.