Ask HN: Software to Manage Notifications

Many applications have this: transactional notifications, where you get an e-mail or a push message when another user edits an item that you are subscribed to. Some notifications may come at the end of the day in a daily digest. If you get notifications of a category you're no longer interested in, you go to your profile screen and update your preferences.

We are a Java/Spring Boot shop, using AWS. It's clear how to build something like this with a combination of web services, SQS, SNS, SES, etc. All of this isn't rocket science, but there's still a lot of business logic to implement that isn't our core business. I am curious if there's an off-the-shelf solution for the hard parts? Thank you.