I'll update this if I find more. For now, this seems to be a partial solution. It's a Gmail add on (except I don't use Gmail) that adds reminders. The options when setting reminders include cancelling it if someone replies, and to remind everyone in the thread. If you combine those two, it seems like — if you use Gmail's web client and have $23/month you're dying to get rid of — a decent way to add the feature. Source: over 1 year ago

— Filters for the incoming emails Alternatives: About a year ago, I found out, that the guys from https://mailbrew.com/ have an essentially identical product, which I used for a few months myself. The product is quite nice, but for my personal usage it did not work very well. I disliked the reading experience, the email formatting was broken for Outlook on Android for a while and forwarded emails did not look nice... - Source: Hacker News / about 1 year ago

I looked at this a few months ago and ended up using mailbrew.com. It's free. Source: over 1 year ago

Https://mailbrew.com/ has helped me since instead of browsing reddit for hours and hours... It kind of just gives me the top three of things I'm interested in (like this post). Source: over 1 year ago

Https://mailbrew.com/ Not a Mac specific app, but a webapp for taming inbox overload You can create your own newsletter from favorite sources. Source: over 1 year ago

What is the font Mailbrew uses in their website headings? Thank you). Source: about 2 years ago