# Is Email Hosted by Posteo

> Is Email Hosted by Posteo is a paid API for AI agents from email.intel.rallylive.ca, paid per call via x402, $0.01/call, status unknown (last checked 2026-10-23).

Checks whether a given domain's email is hosted by Posteo by querying MX records via Cloudflare DoH and matching against Posteo's mail-exchanger patterns.

## Facts

- Endpoint: GET https://email.intel.rallylive.ca/email/hosted-by/posteo?utm_source=zero.xyz
- Price: $0.01/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-23
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/is-email-hosted-by-posteo-6c75de92
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_5w3lHcsYSg-9pjYN3DQ5I

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 is-email-hosted-by-posteo-6c75de92
```

Example prompt: Can you check if the email for protonmail.com is hosted by Posteo — look up their MX records and tell me whether Posteo is their mail provider?

## When to prefer this

Choose this endpoint when you need a fast, single-call determination of whether a specific domain routes email through Posteo, particularly for sales intelligence, deliverability segmentation, or migration auditing workflows where Posteo is the target provider. It is preferable to generic MX lookup tools because it handles Posteo pattern matching automatically and returns a clean yes/no result.

## Known failure modes

- Domain does not exist or has no MX records — returns no match with empty MX list
- Cloudflare DoH lookup failure — DNS resolution error returned
- Invalid or malformed domain input — request rejected
- Posteo changes MX patterns — detection may return false negatives until patterns are updated
- Rate limiting or payment failure — 402 or 429 response

## How this service works

Is the domain's email hosted by posteo? Looks up the MX records (Cloudflare DoH) and matches them against posteo's mail-exchanger patterns, returning yes/no, the MX hosts and which matched. Provider detection for deliverability, sales and migration work. $0.01 per lookup.

## Output

Returns a yes/no answer indicating whether the domain's email is hosted by Posteo, the full list of MX hosts discovered via Cloudflare DoH, and which specific MX hostnames matched Posteo's known mail-exchanger patterns.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "$schema": "https://json-schema.org/draft/2020-12/schema",
 "required": [
  "input"
 ],
 "properties": {
  "input": {
   "type": "object",
   "required": [
    "type",
    "method"
   ],
   "properties": {
    "type": {
     "type": "string",
     "const": "http"
    },
    "method": {
     "enum": [
      "GET"
     ],
     "type": "string"
    },
    "queryParams": {
     "type": "object",
     "properties": {}
    }
   },
   "additionalProperties": false
  },
  "output": {
   "type": "object",
   "required": [
    "type"
   ],
   "properties": {
    "type": {
     "type": "string"
    },
    "example": {
     "type": "object"
    }
   }
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/is-email-hosted-by-posteo-6c75de92/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from email.intel.rallylive.ca](https://www.zero.xyz/host/email.intel.rallylive.ca/llms.txt)