API reference
import SpamScanner from 'spamscanner'; // ESM
const SpamScanner = require('spamscanner'); // CommonJS
const scanner = new SpamScanner(options);
const result = await scanner.scan(rawMessage, scanOptions);Create one scanner and reuse it: it loads the model once and caches DNS and language model answers.
Options#
Every option can be passed to the constructor. Most can also be passed to scan() for one message, which merges them over the constructor's.
| Option | Default | Meaning |
|---|---|---|
threshold | 5 | Score at which a message is spam |
rejectThreshold | 15 | Score at which action is reject |
scores | {} | Points per test: setting keys or test names (tests and scores) |
classifier | bundled model | A Classifier, a model object, a model file path, or false |
classifierOptions | {} | Options for the bundled model (see Classifier) |
allowedLanguages | [] | ISO 639-1 codes; other languages get LANGUAGE_NOT_ALLOWED |
phishing.cloudflare | true | Ask Cloudflare's filtering resolvers about link hosts |
phishing.adult | true | Also ask the family resolver, which blocks adult sites |
phishing.maxHosts | 25 | Link hosts looked up per message |
phishing.homograph | {} | brands (replace the built-in list), extraBrands, allowlist (domains never flagged), strictMode |
dnsbl | {ip: [], domain: []} | DNS blocklist zones for the client IP and for link domains |
dns | {servers: null, timeout: 3000} | Name servers for DNS checks (default: the system's) |
attachments | true | Inspect attachments |
macros | true | Flag macros, active PDFs and RTF objects |
arbitrary | true | Run the rules |
authentication | false | true, or {dnsServers, timeout, mta, weights}: SPF, DKIM, DMARC, ARC |
reputation | false | {allowlist, denylist, apiUrl, headers, timeout} |
allowlist, denylist | IP addresses, domains or addresses; shorthand for reputation | |
clamav | false | true (default socket), {socket} or {host, port} |
llm | null | Language model settings, with mode, minScore, maxScore |
toxicity | false | {model, threshold = 0.7}: a model whose classify([text]) answers like @tensorflow-models/toxicity |
nsfw | false | {model, threshold = 0.6}: a model whose classify(imageBuffer) answers like nsfwjs |
maxLength | 100000 | Characters of body text read |
timeout | 10000 | Milliseconds allowed for each network check |
session | {} | Default SMTP session details |
scan() also takes session:
await scanner.scan(raw, {
session: {
remoteAddress: '203.0.113.5', // the client's IP address
resolvedClientHostname: 'mx.example.com', // its verified reverse DNS name
helo: 'mx.example.com',
envelope: {
mailFrom: {address: 'alice@example.com'},
rcptTo: [{address: 'bob@example.org'}],
},
},
});A server that has already checked SPFSender Policy Framework: a DNS record listing the servers allowed to send mail for a domain., DKIMDomainKeys Identified Mail: a signature over a message, checked with a public key published in the sender's DNS., DMARCA DNS policy telling receivers what to do when mail claiming a domain fails SPF and DKIM alignment. and ARCAuthenticated Received Chain: signatures that carry authentication results across forwarding servers. (with mailauth) can pass its results as authenticationResults, and they are scored instead of checked again:
import {authenticate} from 'mailauth';
const auth = await authenticate(raw, {ip, helo, sender, mta});
await scanner.scan(raw, {authenticationResults: auth});Methods#
| Method | Returns |
|---|---|
scan(source, options) | The result. source is a Buffer, string, Uint8Array or readable stream |
scanFile(path, options) | The result for a message file |
learn(source, 'spam' | 'ham') | Teaches the classifier one message |
unlearn(source, 'spam' | 'ham') | Undoes learn |
saveModel(path, options) | Writes the classifier to a file (options: minCount, maxFeatures, metadata) |
getClassifier() | The Classifier in use, or null |
getClassification(features) | The classifier's verdict for features from getFeatures |
getFeatures(mail) | {features, words, language, script, links, hosts, text, hidden} of a message |
getTokens(text, locale) | The words of a text |
getTokensAndMailFromSource(source) | {tokens, features, mail} |
parse(source) | {raw, mail}, with mail from mailparser |
In getFeatures, text is the text a mail client shows, which the words are read from, and hidden how many characters of text the HTML hides.
scanner.metrics holds totalScans, averageTime and lastScanTime.
The result#
{
isSpam: true,
score: 16.25,
threshold: 5,
rejectThreshold: 15,
action: 'reject', // 'accept', 'tag' or 'reject'
message: 'Spam (BAYES_999, PHISHING_LOOKALIKE_DOMAIN, DECEPTIVE_LINK, FROM_NAME_BRAND)',
tests: [
{name: 'BAYES_999', score: 6.25, description: 'Classifier spam probability 99.9%'},
{name: 'PHISHING_LOOKALIKE_DOMAIN', score: 5, description: '"paypa1-secure.top" imitates paypal by swapping characters'},
// ...
],
results: {
classification: {probability, category, spam, ham, clues, coverage},
phishing: [], // lookalike domains, deceptive links, Cloudflare and URIBL findings
uncheckedHosts: 0, // link hosts beyond phishing.maxHosts, not looked up
attachments: [], // every attachment finding
executables: [], // the executable findings among them
macros: [], // macros, active PDFs, RTF objects
viruses: [], // ClamAV findings: {filename, virus: [names], message}
arbitrary: [], // rules strong enough to mark spam alone
obfuscation: {invisible, mixed, styled},
authentication: null, // mailauth's results with a score, when checked
reputation: null,
dnsbl: [], // {zone, value} for each listing
language: {language, script, notAllowed},
llm: null, // the language model's verdict, when asked
toxicity: [],
nsfw: [],
idnHomographAttack: {detected, domains, riskScore},
},
links: ['http://paypa1-secure.top/login'],
language: 'en',
tokens: ['dear', 'customer', /* ... */],
mail: {/* the parsed message, from mailparser */},
version: '7.0.0',
metrics: {totalTime: 42},
}Findings in phishing, attachments, executables, macros, viruses and arbitrary are objects with a type and a message. String(finding) is the message.
Exports#
import SpamScanner, {
Classifier, getFeatures, segmentWords, detectLanguage,
LLMClassifier, PROVIDERS, RECOMMENDED_MODELS, CLASSIFIER_MODELS,
DEFAULT_SCORES, scoreResults, spamHeaders, rewriteMessage,
loadModel, saveModel, defaultModelPath, loadDefaultModel,
train, evaluate, readExamples,
MilterServer, createHttpServer, createTcpServer, createSpamdServer,
DEFAULTS, VERSION,
} from 'spamscanner';
import ArfParser from 'spamscanner/arf';Classifier#
const classifier = new Classifier({spamCutoff: 0.99, hamCutoff: 0.2});
classifier.learn(getFeatures(mail).features, 'spam');
classifier.classify(features); // {probability, category, spam, ham, clues, coverage}| Option | Default | Meaning |
|---|---|---|
strength, unknown | 0.45, 0.5 | Robinson's s and x: how strongly rare features are pulled toward 0.5 |
minDistance | 0.1 | Features closer to 0.5 than this are ignored |
maxClues | 150 | Strongest features combined per message |
hamCutoff, spamCutoff | 0.2, 0.99 | Bounds of the unsure range |
minLanguageExamples, languageShare | 1000, 0.02 | Messages of each class needed in a language for full confidence |
languagePrior | true | Weigh words against their own language's counts |
merge(other), toJSON(options), Classifier.fromJSON(json), size and entries() are also available.
Training#
import {train, evaluate, saveModel} from 'spamscanner';
const {classifier, spam, ham} = await train({
spam: ['/mail/Junk'],
ham: ['/mail/Archive', '/mail/archive.mbox'],
datasets: [{file: 'extra.csv', textColumn: 'body', labelColumn: 'kind'}],
});
saveModel(classifier, 'model.json');evaluate(classifier, examples) takes {label, features} items, or readExamples(sources), which reads the same sources as train, and returns counts, precision, recall, F1, accuracy and false positive, false negative and unsure rates.
Servers#
import SpamScanner, {MilterServer, createHttpServer, createSpamdServer} from 'spamscanner';
const scanner = new SpamScanner({authentication: true});
const milter = new MilterServer(scanner, {reject: true, rejectCode: 451, subjectTag: '[SPAM]'});
milter.on('scan', ({session, result}) => console.log(session.remoteAddress, result.score));
await milter.listen(7831);
createHttpServer(scanner, {token: process.env.SPAMSCANNER_TOKEN}).listen(7832, '127.0.0.1');
createSpamdServer(scanner).listen(783, '127.0.0.1');ARF reports#
spamscanner/arf reads and writes abuse feedback reports (RFC 5965), the format mailbox providers use to report spam complaints:
import ArfParser from 'spamscanner/arf';
const report = await ArfParser.parse(rawReport);
console.log(report.feedbackType, report.sourceIp, report.originalHeaders.subject);
const raw = ArfParser.create({
feedbackType: 'abuse', userAgent: 'MyService/1.0',
from: 'abuse@example.com', to: 'fbl@example.net',
originalMessage, sourceIp: '192.0.2.1',
});ArfParser.tryParse() returns null instead of throwing for messages that are not reports, and isArfMessage(mail) checks a parsed message.