# Mermail Agent Email Reply

> Mermail Agent Email Reply is a paid API for AI agents from console.mermail.app, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-11).

Send a reply to a specific email in an AI agent's mailbox, queuing the outbound message with optional CC/BCC, HTML body, and attachments

## Facts

- Endpoint: POST https://console.mermail.app/api/agent/v1/mailboxes/%7BmailboxId%7D/emails/%7BemailId%7D/reply?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-11
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/mermail-agent-email-reply-f8af9d6f
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_V2zYwi6OUfIC3gxIoQ12r

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability mermail-agent-email-reply-f8af9d6f -d '<json body>'
```

Example prompt: Reply to the email I just received in my Mermail agent inbox — tell the customer 'Thanks for reaching out, we'll process your refund within 2 business days' and CC billing@mycompany.com on it.

## When to prefer this

Use this endpoint when an AI agent needs to send an outbound reply to a specific email it has already received in its Mermail managed mailbox — particularly for agentic workflows around customer support, sales lead nurturing, or any scenario where the agent must continue an existing email thread rather than initiate a new one.

## Known failure modes

- Invalid mailboxId or emailId returns 404 not found
- Malformed email addresses in to/cc/bcc fields cause validation errors
- Missing required authentication or insufficient payment (x402) causes 402 Payment Required
- Empty message body (both text and html absent) may be rejected
- Invalid UUID for client_send_id returns 400 bad request
- Network timeout without confirmation of queueing

## How this service works

An inbox and wallet for your AI agent. Find and nurture sales leads, resolve customer support, and handle online purchases with controlled payments.

## Output

Returns a JSON object with a 'status' field set to 'queued', confirming the reply has been accepted and scheduled for delivery from the agent's mailbox.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "cc": {
   "oneOf": [
    {
     "type": "string"
    },
    {
     "type": "array",
     "items": {
      "type": "string",
      "format": "email"
     }
    }
   ]
  },
  "to": {
   "oneOf": [
    {
     "type": "string"
    },
    {
     "type": "array",
     "items": {
      "type": "string",
      "format": "email"
     }
    }
   ]
  },
  "bcc": {
   "oneOf": [
    {
     "type": "string"
    },
    {
     "type": "array",
     "items": {
      "type": "string",
      "format": "email"
     }
    }
   ]
  },
  "from": {
   "oneOf": [
    {
     "type": "string"
    },
    {
     "type": "object",
     "required": [
      "email",
      "name"
     ],
     "properties": {
      "name": {
       "type": "string"
      },
      "email": {
       "type": "string",
       "format": "email"
      }
     }
    }
   ]
  },
  "html": {
   "type": "string"
  },
  "text": {
   "type": "string"
  },
  "subject": {
   "type": "string"
  },
  "thread_id": {
   "type": "string"
  },
  "references": {
   "type": "array",
   "items": {
    "type": "string"
   }
  },
  "attachments": {
   "type": "array",
   "items": {
    "type": "object"
   }
  },
  "in_reply_to": {
   "type": "string"
  },
  "client_send_id": {
   "type": "string",
   "format": "uuid"
  },
  "source_draft_id": {
   "type": "string"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "status": "queued"
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/mermail-agent-email-reply-f8af9d6f/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from console.mermail.app](https://www.zero.xyz/host/console.mermail.app/llms.txt)