# StableEmail Update Subdomain Inbox Settings

> StableEmail Update Subdomain Inbox Settings is a free API for AI agents from StableEmail at stableemail.dev, callable via MPP, Free, status unknown (last checked 2026-10-10).

Updates the forwarding address and message retention settings for a subdomain inbox on StableEmail

## Facts

- Endpoint: POST https://stableemail.dev/api/subdomain/inbox/update?utm_source=zero.xyz
- Price: Free
- Payment: MPP
- Status: unknown
- Last checked: 2026-10-10
- Activations on Zero: 0
- Provider: StableEmail
- Docs: https://stableemail.dev
- Website: https://stableemail.dev
- Tags: email, send, inbox, forwarding, subdomain, social
- Canonical page: https://www.zero.xyz/c/stableemail-update-8f8576c6
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_H3TWoOHoMc8v5mHFvSgwb

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 stableemail-update-8f8576c6 -d '<json body>'
```

Example prompt: Update my StableEmail subdomain inbox — subdomain 'mycompany', local part 'hello' — so it forwards to alice@example.com and retains messages.

## When to prefer this

Use this endpoint when you need to change the forwarding destination or retention behavior of an existing subdomain inbox on StableEmail. This is free and does not require purchasing a new inbox. Prefer this over other endpoints when the inbox already exists and you only need to reconfigure its settings rather than create or top up.

## Known failure modes

- Invalid subdomain format — must be 3-30 lowercase alphanumeric characters with hyphens, no double hyphens
- Invalid localPart format — must be 1-64 lowercase alphanumeric characters with allowed symbols
- Invalid forwardTo email address format
- Subdomain does not exist or is not owned by the caller
- Missing required fields subdomain or localPart returns validation error

## How this service works

Update subdomain inbox settings (free)

## Output

A confirmation response indicating the subdomain inbox settings have been updated, reflecting the new forwarding address (or null to disable forwarding) and message retention preference.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "required": [
  "subdomain",
  "localPart"
 ],
 "properties": {
  "forwardTo": {
   "anyOf": [
    {
     "type": "string",
     "format": "email",
     "pattern": "^(?!\\.)(?!.*\\.\\.)([A-Za-z0-9_'+\\-\\.]*)[A-Za-z0-9_+-]@([A-Za-z0-9][A-Za-z0-9\\-]*\\.)+[A-Za-z]{2,}$"
    },
    {
     "type": "null"
    }
   ]
  },
  "localPart": {
   "type": "string",
   "pattern": "^[a-z0-9][a-z0-9._+-]{0,62}[a-z0-9]$",
   "maxLength": 64,
   "minLength": 1
  },
  "subdomain": {
   "type": "string",
   "allOf": [
    {
     "pattern": "^[a-z0-9][a-z0-9-]{1,28}[a-z0-9]$"
    },
    {
     "pattern": "^(?!.*--)"
    }
   ]
  },
  "retainMessages": {
   "type": "boolean"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/stableemail-update-8f8576c6/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from stableemail.dev](https://www.zero.xyz/host/stableemail.dev/llms.txt)