I'm looking for a way to have email subscribers database within Craft without using third-party solutions such as MailChimp.
I'm going to let users enter their emails to subscribe to site categories / channels and then send custom notifications with Postmaster plugin. Pre-defined subscriptions lists will not work for me.
I also don't have membership system.
So I wonder if there's any way to have subscribers database within Craft? Some plugin that people could use to submit their email and area of interest to subscribe and also to unsubscribe?