Drift Developer Platform - Build bots for marketing & sales
TL;DR Email - Send short emails & read emails as fast as you read Facebook
DriftBot - A chatbot for your knowledge base
Spark Mail - Spark helps you take your inbox under control. Instantly see what’s important and quickly clean up the rest. Spark for Teams allows you to create, discuss, and share email with your colleagues
Quip Inbox - A smart and useful new inbox for living documents
mlist - Email newsletters, outside of the inbox