For machines
WarmInboxes for AI agents
Everything here is callable without an account. 15 live deliverability checks over MCP or plain HTTP, and machine-readable descriptions of both. Ordering and running the infrastructure itself is a separate, authenticated API — the boundary is at the foot of this page.
What an agent can do here
Every check queries live DNS, registries and blacklists at call time. Nothing is cached, and none of these endpoints store the domain or address you pass them.
| Check | MCP tool | HTTP endpoint | Parameters |
|---|---|---|---|
| Deliverability grade (A-F) | check_deliverability | check-deliverability | domain |
| SPF record | check_spf | check-spf | domain |
| DKIM record | check_dkim | check-dkim | domain, selector |
| DMARC record | check_dmarc | check-dmarc | domain |
| BIMI record | check_bimi | check-bimi | domain |
| MTA-STS policy | check_mta_sts | check-mta-sts | domain |
| DNS records | check_dns | check-dns | domain, type |
| Blacklist / RBL check | check_blacklist | check-blacklist | input |
| SURBL URI blacklist (bulk) | check_surbl | check-surbl | domains (comma-separated) |
| Nameservers and DNS provider (bulk) | check_nameservers | check-nameservers | domains (comma-separated) |
| Domain registration and expiry | check_domain_expiry | check-domain-expiry | domain |
| Google Workspace tenancy | check_google_domain | check-google-domain | domain |
| CNAME chain | check_cname | check-cname | host, expected |
| Email verification (bulk) | verify_email | verify-email | emails (comma-separated) |
| ESP segmentation (bulk) | segment_esp | segment-esp | domains (comma-separated) |
There are 33 tools on the site in total; the 15 above are the ones with an endpoint behind them. The rest run in the browser — see all of them.
MCP
Streamable HTTP, no authentication, no signup. Add it as a remote server and the checks appear as typed tools. A plain GET on the endpoint returns the server info and the tool list without a handshake, which is the quickest way to see what is there.
{
"mcpServers": {
"warminboxes": {
"url": "https://warminboxes.com/mcp"
}
}
}https://warminboxes.com/mcp
HTTP API
Every check is also a plain endpoint. GET with query parameters or POST with a JSON body; both return JSON. No key, no signup, CORS open. Please be reasonable with volume — there is no rate-limit key to ask for, which only works while nobody abuses it.
curl "https://warminboxes.com/.netlify/functions/check-deliverability?domain=stripe.com"Described in full at /openapi.json.
Machine-readable files
- /llms.txtWhat this site is, its pages, its tools and its API, as prose.
- /llms-full.txtEvery page on the site as plain text, in one fetch.
- /tools.jsonThis table as JSON: each tool with its category, endpoint and MCP name.
- /openapi.jsonOpenAPI 3.1 for the free API, generated from the table that answers it.
- /price.mdEvery price, both products, every billing cycle.
- /sitemap.xmlEvery URL.
Every page also has a markdown twin: append .md to its URL.
What needs authentication
No key. Read-only: these look things up and change nothing.
Ordering inboxes and domains, and managing them. Bearer token, documented separately — do not infer its endpoints from the free ones.
Appropriate use
These are the tools our own agency runs on, published so anyone can check a domain before sending to it. Use them to diagnose infrastructure you own or are working on. They are not for enumerating someone else's estate at volume, and the bulk endpoints exist so one caller can check their own list in a single request rather than hammering the single-domain ones.
Browse the tools a human would use