DHH announced on the Ruby on Rails blog the details behind Action Mailbox, the second brand new framework coming to Rails 6 (the first was Action Text). Action Mailbox routes incoming emails to controller-like mailboxes for processing in Rails.

The framework was, like Action Text and Active Storage, extracted from Basecamp 3. We’ve been using a related approach to route everything from forwarded emails to email replies to messages and discussions. After extracting the ideas into Action Mailbox, we reintegrated the framework into Basecamp, and we’ve been running the code we’re sharing today for over a month in production.