Nah, not DIY. I was curious about in-app notifications, yes, and you're right about a dynamic data store. But that's another service to maintain and support, so it never seems to get on the roadmap. Also, sometimes the messages need something special like a checkbox "I agree to new T&C's", etc, which requires new code (at least, the first time round), and storage of who agreed and didn't.
Hadn't heard of Courier.com so will check that out.
Hadn't heard of Courier.com so will check that out.