Upstream

Upstream is a messaging app for teams that keeps email as the underlying communication layer while adding a shared, channel-style workspace. It groups work into split inboxes and channels, lets teammates discuss messages with comments, and uses AI to draft replies in a chosen voice and identify messages that need a response or follow-up. Core gives a small team a practical way to test the workflow: it supports up to five seats, seven AI draft replies and three smart follow-ups per week, custom voice settings for as many as three audiences, unlimited channels and search, and mobile access. Pro removes the weekly AI limits, expands voice controls, adds private channels, unlimited members and history, multiple-account use, one-to-one training, and removes the Upstream signature. Max adds personal AI agents, team-wide AI automations, enterprise security and governance, plus dedicated onboarding and support. The product suits teams that want collaborative email handling without moving external conversations into a separate chat system. Buyers should weigh its per-member annual billing against the value of shared inbox context, and confirm that its email-centered workflow fits their account setup and governance requirements.