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@lacspace/mail-auth

v1.0.0Mail Kit0 deps

Email authentication-result parsing and phishing/impersonation heuristics for webmail warning banners. RFC 8601 Authentication-Results parser (SPF, DKIM, DMARC, ARC, Received-SPF fallback, trusted authserv-id selection so forged lower headers are ignored) plus assessRisk(): DMARC/SPF/DKIM failures, reply-to mismatch, display-name address tricks, known-contact impersonation, lookalike domains (edit distance, homoglyph skeletons, punycode, mixed scripts, subdomain/hyphen/TLD tricks), free-mail brand claims, payment-change and credential-lure wording in English and Nepali, deceptive links. Plain-English reasons, 0-100 score, none/low/high level. Zero dependencies, isomorphic.

npm i @lacspace/mail-auth
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Usage

mail-auth.ts
import { parseAuthenticationResults, assessRisk } from "@lacspace/mail-auth";

const auth = parseAuthenticationResults(
  { authenticationResults: headers.getAll("Authentication-Results"), receivedSpf: headers.getAll("Received-SPF") },
  { trustedAuthservIds: ["mx1.yourmail.com"] }, // only YOUR server's header
);
// { spf: "pass", dkim: "pass", dmarc: "fail", dmarcPolicy: "reject", headerFrom: "lacsp4ce.com", authservId: "mx1.yourmail.com", … }

const risk = assessRisk({
  from: { name: "Lacspace Billing", address: "billing@lacsp4ce.com" },
  replyTo: [{ address: "lacspace.billing@gmail.com" }],
  subject: "[EXTERNAL] Updated bank details",
  snippet: "Our bank details have changed, please pay the attached invoice urgently.",
  auth,
  recipientDomain: "lacspace.com",
  knownContacts: addressBook,             // [{ name, address }]
  links,                                  // [{ href, text }] from your HTML sanitizer
});
// { level: "high", score: 100, reasons: [
//   "The sender's address (billing@lacsp4ce.com) looks like lacspace.com but is a different domain.",
//   "It failed lacsp4ce.com's anti-forgery check (DMARC), so it may not really be from them.",
//   "It urgently asks for a payment or new bank details. Confirm with the sender by phone before paying.",
//   … ], signals: [{ code: "lookalike.from", weight: 50, detail: "lacspace.com" }, …] }

Exports 14

FREE_MAIL_DOMAINSRISK_THRESHOLDSSIGNAL_WEIGHTSassessRiskdecodePunycodeeditDistancehasMixedScriptisFreeMailisWholeScriptConfusablelookalikeOfparseAuthenticationResultsregistrableDomainskeletontoUnicodeDomain

Keywords

emailauthentication-resultsrfc8601spfdkimdmarc

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