Email Deliverability Check

Score a domain's email deliverability from 0 to 100 from its SPF, DKIM, DMARC, mail servers and blocklist status.

Pay by wallet (x402) email-deliverability-check

Example

Input

{
  "domain": "google.com"
}

Answer

{
  "spf": {
    "valid": true,
    "exists": true,
    "record": "v=spf1 include:_spf.google.com ~all",
    "mechanism": "~all (soft fail)"
  },
  "dkim": {
    "detected": false,
    "selector_found": null
  },
  "dmarc": {
    "exists": true,
    "policy": "reject",
    "record": "v=DMARC1; p=reject; rua=mailto:[email protected]"
  },
  "grade": "B",
  "score": 80,
  "domain": "google.com",
  "issues": [
    "No DKIM record found for common selectors"
  ],
  "mx_records": [
    {
      "exchange": "smtp.google.com",
      "priority": 10
    }
  ],
  "blacklisted": false,
  "recommendations": [
    "Configure DKIM signing and publish a DKIM DNS record. Note: custom selectors may exist but were not detected."
  ],
  "blacklists_checked": [
    {
      "name": "zen.spamhaus.org",
      "listed": false
    },
    {
      "name": "bl.spamcop.net",
      "listed": false
    },
    {
      "name": "b.barracudacentral.org",
      "listed": false
    }
  ]
}

Inputs

Field	Type	Required	What it is
`domain`	string	Yes	—

Output fields

How reliably each field appears in a successful answer.

Field	Type	Appears
`spf`	object	Always (present in every successful answer)
`dkim`	object	Always (present in every successful answer)
`dmarc`	object	Always (present in every successful answer)
`grade`	string	Always (present in every successful answer)
`score`	number	Always (present in every successful answer)
`blacklisted`	boolean	Always (present in every successful answer)

How to call it

The same tool through each route. MCP clients reach it through Strale’s server at https://api.strale.io/mcp; the call below is what the agent sends.

# Needs an API key. max_price_cents caps what this call may cost.
curl -X POST https://api.strale.io/v1/do \
  -H "Authorization: Bearer $STRALE_API_KEY" \
  -H 'Content-Type: application/json' \
  -d '{
    "capability_slug": "email-deliverability-check",
    "inputs": {
      "domain": "google.com"
    },
    "max_price_cents": 5
  }'

{
  "tool": "strale_execute",
  "arguments": {
    "slug": "email-deliverability-check",
    "inputs": {
      "domain": "google.com"
    },
    "max_price_cents": 5
  }
}

import { Strale } from "straleio";

const strale = new Strale({ apiKey: process.env.STRALE_API_KEY! });
const result = await strale.do({
  capability_slug: "email-deliverability-check",
  inputs: {
    "domain": "google.com"
  },
  max_price_cents: 5,
});

import os
from straleio import Strale, DoRequest

strale = Strale(api_key=os.environ["STRALE_API_KEY"])
result = strale.do(DoRequest(
    capability_slug="email-deliverability-check",
    inputs={
        "domain": "google.com",
    },
    max_price_cents=5,
))

# No account. The first request answers 402 with the price in USDC;
# an x402 client pays it from your wallet and repeats the request.
curl -i 'https://api.strale.io/x402/v2/email-deliverability-check?domain=google.com'

Limitations

SMTP checks do not guarantee delivery
SMTP verification may be blocked by some mail servers — a 'deliverable' result is not guaranteed delivery
What to do instead: Treat SMTP-verified results as 'likely deliverable' and implement bounce handling in your email pipeline for definitive status