Ask HN: How to Do Email Transparency?

In 2013, Stripe posted a few articles regarding [Scaling Email Transparency](https://news.ycombinator.com/item?id=8718414). It seems like a good approach to sharing information among a team of less than 100 people.

Specifically, it seemed to be:

- Less of a hassle and more easily searchable than Slack.

- More user-friendly than a Discourse instance.

However, the tool Stripe used for managing Email Transparency with Google Groups, is [no longer being updated](https://github.com/stripe/gaps). What tools are currently used, in Stripe or smaller orgs, to achieve Email Transparency?