Email Communication

Your agent communicates via email — the default interface. This guide explains how the email system works.

Email address

Every agent gets its own email address — a unique name:

swiftpebble@tinyfat.com
calmflint@tinyfat.com
brightember@tinyfat.com

This is a real email address. You can send to it from Gmail, Outlook, Apple Mail, your phone — anywhere. Your agent’s replies come from the same address.

The email flow

You → yourname@tinyfat.com
         ↓
   Resend webhook → Platform
         ↓
   Verify signature, resolve agent
         ↓
   Validate sender (allowed_senders)
         ↓
   Enqueue to webhook queue
         ↓
   Wake sandbox, mount R2, start troublemaker
         ↓
   Agent processes message (one turn)
         ↓
   Agent writes to /data/outbox/email/
         ↓
   Platform sends email via Resend
         ↓
You ← yourname@tinyfat.com

Response time

• Cold start: 30-60 seconds (container boot + troublemaker init)
• Warm: 10-20 seconds (agent thinking)
• Simple queries: Faster with Haiku model

The agent runs one “turn” per email — it processes your message, uses tools if needed, and responds.

Allowed senders

Only whitelisted email addresses can trigger your agent. This prevents:

• Spam triggering expensive API calls
• Unauthorized access to your agent

How allowed senders work

Your signup email is automatically added when you create the agent. Additional senders can be configured — management UI is coming soon.

Supported match types:

• Exact match: alice@example.com — only this address
• Domain wildcard: @company.com — anyone at that domain

Caution

Be careful with domain wildcards. @gmail.com would allow any Gmail user to email your agent.

Email commands

Send commands in the subject line or at the start of the email body:

Command	Effect
/clear	Start a fresh session
/resume	List recent sessions
/resume abc1	Resume specific session by hash
/compact	Compress context to save tokens
/model	Show current model
/model haiku	Switch to Haiku (fastest)
/model sonnet	Switch to Sonnet (balanced)
/model opus	Switch to Opus (most capable)

Example: Switching models

To: yourname@tinyfat.com Subject: /model sonnet Body: (empty or anything)

Attachments

You can send attachments to your agent:

• Images: Agent can view and analyze (PNG, JPG, GIF, WebP)
• Documents: Agent can read text content (PDF, TXT, MD)
• Files: Agent can process data (JSON, CSV, etc.)

Attachments are fetched from Resend’s API and delivered to the agent.

Tip

For large files, consider uploading to a URL and sending the link instead.

Sending email from your agent

Your agent writes emails to /data/outbox/email/:

{
  "to": ["recipient@example.com"],
  "subject": "Report ready",
  "body": "Here's the analysis...",
  "status": "pending"
}

The platform picks these up and sends them. See Email JSON Reference.

Threading

Responses maintain proper threading:

• In-Reply-To header links to your original message
• References header includes the full chain
• Gmail, Outlook, Apple Mail all group replies correctly

Note

If threading breaks, check that your email client is using standard headers. Some corporate email systems modify headers.

Email-based signup

Special addresses trigger provisioning:

• start@tinyfat.com — Creates a new agent for the sender
• go@tinyfat.com — Same as start@
• demo@tinyfat.com — Ephemeral demo agent (rate limited)

Delivery issues

Email not received

1. Check spam/junk folder
2. Verify allowed senders includes your address
3. Check dashboard for errors

Agent didn’t respond

1. Check if sender is whitelisted
2. Look for errors in dashboard
3. Check dashboard for errors

Response went to spam

Add yourname@tinyfat.com to your contacts or mark as “not spam”.

Next steps

• Email JSON Reference — Full outbox format
• Troubleshooting — Common issues
• Dashboard — Managing your agent