sixel.email

Not an inbox. A lifeline.

A locked-down 1:1 channel between you and your AI agent. It can only email you. Only you can email it. If it stops responding, you'll know.

Works with OpenClaw, Claude Code, and anything with curl.

How it works

1. Sign up. Pick an agent address.
2. Set the one email it's allowed to talk to (yours).
3. Get an API key. 10,000 free messages.
4. Paste 5 lines into your agent config. Done.

The dead man's switch

Your agent polls GET /v1/inbox to check for messages. If it stops polling, Sixel notices. You get an alert email.

No extra health check infrastructure. No uptime service. The channel itself is the liveness monitor.

The agent integration

You have an email address for contacting me when you're stuck.
API: https://sixel.email/v1
Token: sm_live_xxxxx
Use POST /v1/send to email me. Use GET /v1/inbox to check for my reply.
Poll /v1/inbox every 60 seconds while waiting.

The API

POST  /v1/send                        Send an email (with optional attachments)
GET   /v1/inbox                        Poll for new messages (also the heartbeat)
GET   /v1/inbox/:id                    Get a specific message
GET   /v1/inbox/:id/attachments/:aid   Download an attachment
POST  /v1/rotate-key                   Rotate the API key

Security

• Outbound: Your agent can only email the one address you set. No exceptions — enforced server-side.
• Inbound: Only emails from your allowed contact are delivered. Unknown senders are dropped at the edge (DKIM-validated).
• Door Knock: Optional nonce authentication for inbound messages. When enabled, every reply requires a single-use token. How it works →
• Kill switch: Rotate the API key to cut off the agent instantly. No SSH, no restart needed.

How Sixel is different

Agent-to-agent pipes

Your agents can message each other through Sixel directly. Every message is tee'd to your inbox — you see the full conversation.

Same lockdown. Same heartbeat. Full visibility. Your agents coordinate. You never lose the thread.

Free. Polling is free. No subscription. Donations welcome.