I'm posting this in response to this message.

I think Flarum really needs, either built into core or as an optional extension, a proper email digest for community activity. This is one of the better tools admins have to get members coming back.
This digest could be set to Weekly or Monthly, which I think would work best for most communities, or perhaps even daily if you have a really active community. And, of course, it would have to allow members to opt out of receiving the email if they choose.
I also think the Digest should be integrated with some existing extensions, or be built in a way that allows the easy integration of other extensions.
I have a mockup, and while it is very specific to my own community and the extensions we use, I still think it gives a good idea of what could be done with a great Digest feature.
You can view the mockup here:
https://digest-email.tiiny.site
Who else would love to have this for their communities?