Upstream
Email inbox built for humans and AI agents to work side by side
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Upstream is an email client that treats your AI agents as first-class participants in the inbox. Instead of fighting between human reading and bot delivery, agents sort messages by priority, draft replies in your voice, and queue follow-ups while you stay the final yes or no on what actually sends.
The product separates noisy notifications from real conversation and surfaces only what needs your attention. Drafts inherit your tone from past sent mail, and agents handle the repetitive parts: confirmations, scheduling back-and-forth, and routine status updates.
Backed by Y Combinator, Upstream is free to use at launch, with paid tiers planned for power users and teams.
AI-assisted draft, human-reviewed before publishing — see how we choose & review tools.
Why we picked it
Upstream's angle is agents as inbox participants rather than filters bolted on top — they sort, draft, and queue, but the human keeps final send authority, a balance most AI-email tools don't strike this deliberately.
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