It feels like an automated process where some founder contacts you 7 days after you stop using an app, and often these emails can get a little whiny.
What's worked for me is forums and chat. If you're advertising your product on a forum, see what people say. Chat rooms integrated on a site are a great place to just lurk and passively get feedback.
There was one game I played where the chat was so active it would move off the screen in half a second. But it was filled with user sentiment and feedback.
My only problem now is I don't know how to talk with my old users since they don't reply to my emails and are not aware of the discord server I created
But maybe I could add an in-app survey or just ask people in my discord server to answer them.
Hey, We notice that you have signed up to our app but are not very active on our site. So, we would like to know what we have been doing wrong and how we can improve the app so as to deliver you a better value proposition.
Currently, we have added a few courses for you to check out so give your honest review of them too. Our site: https://enrole.herokuapp.com.
We appreciate any criticism. So feel free to share them so that we can improve our app. Thank You
As @yesenadam suggests, perhaps you could promote your site on Show HN and then you might get some relevant feedback.