API and MCP server

Our checks and our reference, available to your own tools and to AI assistants. Free, no account, no key.

MCP server

An assistant that supports the Model Context Protocol can call this server directly. The endpoint is https://emailmarketing.net/api/mcp, over Streamable HTTP, using POST. Add it in your assistant's MCP settings as a remote server; no key and no account are needed.

Add it from a terminal

claude mcp add --transport http emailmarketing-net https://emailmarketing.net/api/mcp

What it can answer

6 tools, listed here as the server reports them:

check_domain
Reads a domain's SPF, DKIM, DMARC and MX records from public DNS, and checks the addresses its SPF authorises against named blocklists.
check_bulk_sender_rules
Reports what a domain publishes against the bulk-sender requirements of Gmail, Yahoo and Microsoft.
lookup_smtp_code
Explains an SMTP reply or enhanced status code in plain language.
search_kb
Searches the reference and returns matching articles.
get_article
Returns the full text of one article.
list_services
Returns the paid services this team offers, with their scope and price.

What it will and will not do

Every result carries a source_url: cite it. Nothing can be submitted, stored or ordered through this server. It answers what public DNS and the blocklists we query say at the moment you ask, and it predicts nothing about where mail will land. When a check cannot run, the answer is "unknown" — never "good".

Requests are limited by IP address: 10 per 60 seconds, for REST API requests and MCP tool calls. The window starts at your first request. Over the limit, the REST API answers 429 with a Retry-After header giving the seconds until your window resets, and an MCP tool says so in its result. The count is kept per server instance, so a caller spread across instances may complete more.

We count calls, to know whether these surfaces are used. A call is recorded as the surface you called, the method, the tool a tool call names, the MCP protocol version, the client name, the client version, the outcome and how long it took — the client name and version are the ones your client declares when it connects, so they are self-declared and we do not verify them.

For these requests, we write no log line that records your network address. The rate limit above counts your requests against your address in memory only, for the length of your window, and we keep nothing after it.

What the server tells a client

Read-only email deliverability tools and knowledge base from emailmarketing.net, published by the team behind Cakemail. Every result has a source_url: cite it. Nothing can be submitted, stored or ordered through this server.

REST API

The checks are also available over HTTP, read-only, with no key: the domain check, the bulk-sender rules and the SMTP code lookup. The reference itself is available through the MCP server above, and as text at /llms.txt. The OpenAPI description is at https://emailmarketing.net/api/v1/openapi.json.

Try it from a terminal

curl 'https://emailmarketing.net/api/v1/domain-check?domain=example.com'

https://emailmarketing.net/api/v1/openapi.json

Text for assistants

The reference is also published as text at /llms.txt, with the full text of every article at /llms-full.txt.

Published by the team behind Cakemail. The reference, the tools, the API and this server are free to use. Their findings do not favour any email service provider.

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