https://throttlehq.com https://throttlehq.com provides a service similar to what you're looking for. The free tier forwards daily "digests", but the paid tier w

https://throttlehq.com https://throttlehq.com provides a service similar to what you're looking for. The free tier forwards daily "digests", but the paid tier will do direct forwarding using your own domain. I definitely think there's an opportunity for a similar open source self-hosted solution.