inbound-guard

Is this email automated cold outreach? A score, a verdict and the reasons.

npx @analyzemail/inbound-guard message.eml

Most businesses do not send cold email. They receive it, more of it every month, written and followed up by software that never gets tired. inbound-guard reads an incoming message and says whether it was sent the way cold outreach is sent: from a spare domain, through a sequencing tool, in a series of nudges. A CLI for mail rules and scripts, an MCP server for the agent that reads your inbox, and a library for everything else.

Zero dependencies. Nothing about your mail leaves your machine.

What it looks at

The score is the sum, from 0 to 100. 60 or more is cold, 35 to 59 is likely cold, below that is not cold.

Related MCP server: sabit-mcp

Example

$ npx @analyzemail/inbound-guard message.eml

COLD  score 100
  From     dana@getacme.io
  Subject  Quick question about your onboarding

  Sent with a sequencing tool   lemlist  +40
  New domain                    getacme.io registered 23 days ago  +25
  Look-alike sending domain     getacme.io redirects to acme.com  +30
  Replies go to another domain  sent from getacme.io, replies to acme.com  +15
  Sales sequence wording        "Worth a quick chat", "15 minutes", "I came across your"  +24

A whole mailbox export:

$ npx @analyzemail/inbound-guard inbox.mbox --offline
cold      79  dana@getacme.io  Quick question about your onboarding
not_cold   8  priya@example.com  Re: Q4 budget
cold      69  jordan@trynorthwind.com  Re: {{company}} partnership
not_cold   0  news@bigpaper.com  This week — the news

4 messages: 2 cold, 0 likely cold, 2 not cold

Options

--contacts <file>  Addresses or domains you already deal with, one per line.
--offline          Skip the domain age and website lookups.
--fail-on <level>  Exit 1 at this verdict or worse: cold (default) or likely.
--json             Machine-readable output.
--no-colour        Plain text.

Input is a .eml file, an mbox export, or a message on standard input (-).

Exit code 0 means not cold, 1 means cold, 2 means it could not run. So it fits a mail rule or a procmail/sieve pipe:

inbound-guard - --fail-on likely < message.eml || mv message.eml cold/

For agents: MCP server

npx @analyzemail/inbound-guard mcp

{
  "mcpServers": {
    "inbound-guard": { "command": "npx", "args": ["-y", "@analyzemail/inbound-guard", "mcp"] }
  }
}

One tool, check_message: the raw message or the path of a .eml file, and optionally the person's contacts. It tells the agent not to reply on the person's behalf to a cold message, and to show a likely one to the person with the reasons.

Library

import { checkMessage } from '@analyzemail/inbound-guard'

const result = await checkMessage(rawMessage, { contacts: ['acme.com'] })
// { verdict, score, signals: [{ code, label, detail, weight }], from, subject, domain, notes }

What it does not do

It does not move or delete mail. It gives a verdict; your rule or your agent decides what happens next.

It does not send your mail anywhere. Messages are read on your machine. The only network requests are the sending domain's RDAP record (via rdap.org, or INBOUND_GUARD_RDAP_URL) and its home page, to see where it redirects. --offline turns both off. A lookup that fails counts for nothing.

It does not judge the offer. A cold message can be one you want. The score says how a message was sent, not whether it is worth reading.

It is not a spam or phishing filter. That is your mail provider's job. inbound-guard is for the outreach that gets past it.

It cannot see custom tracking domains. Most sequencing tools let a sender use their own tracking domain. The hidden-image and domain checks catch many of those; not all.

Related

• Analyzemail: the other direction too. Verify a list before you send to it, by API or MCP server.

• send-guard and loop-breaker, from our partner AskEleven: checks for agents that send.

License

MIT