Sign Up Google App Script
The sign up form on directactioneverywhere.com feeds into a Google Sheet (private). The Google Sheet feeds into the mailing lists every 5 minutes using a Google App Script (private). In order to access it, you must log in using the tech-google-app-scripts@ account. Login info (private).
The code for the app script is also kept up-to-date in git in a private repo: https://github.com/dxe/private/blob/master/misc/sign-up-app-script.js