# AgentMail Send Message

> AgentMail Send Message is a paid API for AI agents from AgentMail at mpp.api.agentmail.to, paid per call via MPP, $0.01/call, status unknown (last checked 2026-10-12).

Sends an email message from a specified AgentMail inbox

## Facts

- Endpoint: POST https://mpp.api.agentmail.to/v0/inboxes/:inbox_id/messages/send?utm_source=zero.xyz
- Price: $0.01/call
- Payment: MPP
- Status: unknown
- Last checked: 2026-10-12
- Activations on Zero: 0
- Provider: AgentMail
- Docs: https://docs.agentmail.to
- Website: https://agentmail.to
- Tags: email, inboxes, domains, drafts, threads, webhooks, messaging, ai, social
- Canonical page: https://www.zero.xyz/c/agentmail-send-53905c6f
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_CwwsSmJje_UF0fc64TZ8W

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 agentmail-send-53905c6f -d '<json body>'
```

Example prompt: Send an email from my AgentMail inbox 'inbox_abc123' to john@example.com with an allow entry in the send direction — the inbox should be permitted to send to that address.

## When to prefer this

Use this endpoint when an AI agent needs to programmatically send an outbound email from an AgentMail-managed inbox. Prefer this over generic SMTP or other email APIs when the inbox is already provisioned on AgentMail and you need tight integration with AgentMail's threading, drafts, and webhook ecosystem. Ideal for fully automated agent-to-human or agent-to-agent email communication workflows.

## Known failure modes

- Invalid inbox_id returns 404 not found
- Missing required fields (direction, type, entry) returns 400 bad request
- Invalid enum value for type or direction returns 422 unprocessable entity
- Malformed email address in entry field returns 400 validation error
- Unauthorized access to inbox returns 401 or 403
- Inbox does not exist or belongs to another account returns 403 forbidden
- Insufficient USDC balance to cover $0.01 call fee returns payment error

## How this service works

Send message

## Output

Returns a confirmation that the message was sent, along with the sent message record including message ID, timestamp, and delivery status from the AgentMail inbox.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "required": [
  "direction",
  "type",
  "entry"
 ],
 "properties": {
  "type": {
   "enum": [
    "allow",
    "block"
   ],
   "type": "string",
   "title": "ListType",
   "description": "Type of list entry."
  },
  "entry": {
   "type": "string",
   "description": "Email address or domain."
  },
  "direction": {
   "enum": [
    "send",
    "receive",
    "reply"
   ],
   "type": "string",
   "title": "Direction",
   "description": "Direction of list entry."
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/agentmail-send-53905c6f/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from mpp.api.agentmail.to](https://www.zero.xyz/host/mpp.api.agentmail.to/llms.txt)