Upstream - The first inbox designed for humans and agents
Your inbox, handled for you. Agents sort the noise, draft replies in your voice, and follow up automatically.
Hey YC! đź‘‹
We’re Louis Lecat and Jonathan Tiret - co-founders of Upstream.
TL;DR: Upstream is an email client that handles your inbox for you. Agents sort the noise, draft in your exact voice, follow up on time, and do what you ask, so you can finally relax and enjoy email again.
Try it here: Sign up with Google
The problem
We were told AI was going to fix email. Two years in, your inbox looks the same, the drafts sound like ChatGPT, and you stopped clicking on the AI buttons bolted on every product. We wanted an inbox where agents work for you - before you ask - but still let you make the final call.
What we built
We rebuilt email from the ground up as a surface agents can read, write, and act on.
đź“Ą Your inbox is organized
Spam, cold outreach, and low-priority emails are moved out of the way. The conversations that actually need your attention stay front and center.
✍️ Custom voice prompt
Upstream learns how you write from your own emails and drafts replies that sound exactly like you, adapting to who you’re talking to.
🤖 Built-in agent to do what you ask
Find receipts, write personalized emails, schedule meetings, update records, or handle whatever task comes up in your inbox.
⏰ Smart follow-ups
When someone drops the ball, Upstream follows up automatically at the right time so important conversations keep moving.
Open and agent-native
Email is becoming a shared workspace for humans and agents. Upstream is built for both.
🧠Uses your company context
Connect Granola, Notion, Google Drive, and Calendar so agents understand your work before they act.
🔌 Use it from Claude or Codex
Control Upstream over MCP from Claude, Codex, or your own agents. Or bring agents directly into Upstream.
Finally, we made every system prompt fully editable, so that you can configure it to work the way you want.
What users told us
During our closed beta, customers told us they felt more in control of their inbox, and that email had become a fun part of their day again. We’ve seen many people replace Superhuman with Upstream’s free plan.
Our Ask
Try Upstream and let us know what you think. Setup is fully automated and only takes a few minutes - and it’s free!
Link to get started: upstream.do
Thank you!