Features

- MX record validation
- SMTP server connection testing
- DKIM record lookup
- DMARC policy validation
- MTA-STS support (RFC 8461)
- IPv4/IPv6 support
- Local IP blocking
- DNS failover resolvers
- Punycode/IDN support
- TypeScript support

Installation

``bash
npm install email-domain-check


or

pnpm add email-domain-check

or

yarn add email-domain-check

or

bun add email-domain-check
`

Usage (ESM / TypeScript)

`ts
import { Address, DomainChecker } from 'email-domain-check';

const checker = new DomainChecker();

// Check if domain has MX records
const hasMx = await checker.hasMxRecord('user@gmail.com');
console.log('Has MX:', hasMx);

// Get MX records with priority
const mxRecords = await checker.getMxRecord({
target: 'gmail.com', // string, URL or Address
useCache: false,
preferDomainNS: false, // use authoritative ns ns1.google.com
});
console.log('MX Records:', mxRecords);
// [{ exchange: 'gmail-smtp-in.l.google.com', priority: 5 }]

// use url, domain or email
const url = new URL('https://gmail.com');
const addr_01 = Address.loadFromTarget(url);
const addr_02 = Address.loadFromTarget('gmail.com');
const addr_03 = Address.loadFromTarget('user@gmail.com');
const addr_04 = new Address('mehmet.kozan@gmail.com'); // email or domain

console.log('Has MX 01:', await checker.hasMxRecord(addr_01));
console.log('Has MX 02:', await checker.hasMxRecord(addr_02));
console.log('Has MX 03:', await checker.hasMxRecord(addr_03));
console.log('Has MX 04:', await checker.hasMxRecord(addr_04));
// or direct use
console.log('Has MX 05:', await checker.hasMxRecord(new URL('https://gmail.com')));
console.log('Has MX 06:', await checker.hasMxRecord('gmail.com'));
console.log('Has MX 07:', await checker.hasMxRecord('user@gmail.com'));
console.log('Has MX 08:', await checker.hasMxRecord('mehmet.kozan@gmail.com'));
`

Usage (CommonJS)

`js
const { DomainChecker } = require('email-domain-check');

async function run() {
const checker = new DomainChecker();

// Check if domain has MX records
const hasMx = await checker.hasMxRecord('user@gmail.com');
console.log('Has MX:', hasMx);

// Get MX records with priority
const mxRecords = await checker.getMxRecord({
target: 'gmail.com', // string, URL or Address
useCache: false,
preferDomainNS: false, // use authoritative ns ns1.google.com
});
console.log('MX Records:', mxRecords);
// [{ exchange: 'gmail-smtp-in.l.google.com', priority: 5 }]
}

run();
`

Advance Usage

#### Get Records
`ts
import { DomainChecker } from 'email-domain-check';

const checker = new DomainChecker();

// Get SPF record
const spf = await checker.getSpfRecord({
target: 'mehmet.kozan@cambly.com',
dkimSelector: 'k1',
});
console.log('SPF:', spf);

// Get DKIM record
const dkim = await checker.getDkimRecord({
target: 'mehmet.kozan@cambly.com',
dkimSelector: 'k1',
});
console.log('DKIM:', dkim);

// Get DMARC record
const dmarc = await checker.getDmarcRecord({
target: 'gmail.com',
});
console.log('DMARC:', dmarc);

// Get MTA-STS record
const sts = await checker.getStsRecord({
target: 'user@gmail.com',
});
console.log('MTA-STS:', sts);

// Get custom records
const customRecords = await checker.getCustomRecords({
target: 'user@gmail.com',
});
console.log('Custom Records:', customRecords);

// Get custom kv record
const kvRecord = await checker.getCustomKVRecord(
{
target: 'user@gmail.com',
},
'yahoo-verification-key',
);
console.log('KV Record:', kvRecord);

// Get custom kv record
const allKVRecord = await checker.getAllKVRecords({
target: 'user@gmail.com',
});
console.log('All KV Records:', allKVRecord);
`

#### Get Authoritative Name Servers

`ts
import { DomainChecker } from "email-domain-check";
const checker = new DomainChecker();

// Get name servers
const nameServers = await checker.getNameServers("gmail.com");
console.log("Name Servers:", nameServers);


`

#### Get SMTP Connection
`ts
import { DomainChecker } from "email-domain-check";

const checker = new DomainChecker();
// Test or Get SMTP connection for mail sending
const socket = await checker.getSmtpConnection("user@example.com");
if (socket) {
console.log("SMTP connection successful");
socket.end();
}
`

#### MTA-STS Policy
`ts
import { getMtaStsPolicy, isMxAllowed } from "email-domain-check";

const policy = await getMtaStsPolicy("gmail.com");
if (policy) {
console.log("MTA-STS Policy:", policy);
// { version: 'STSv1', mode: 'enforce', mx: ['*.google.com'], max_age: 86400 }

const allowed = isMxAllowed("alt1.gmail-smtp-in.l.google.com", policy);
console.log("MX Allowed:", allowed);
}
`

#### Address Parsing and Validation
`ts
import {Address } from "email-domain-check";
// Address parsing and validation
const addr = Address.loadFromTarget("user@example.com");
console.log("Hostname:", addr.hostname); // example.com
console.log("User:", addr.user); // user
console.log("Is IP:", addr.isIP); // false
console.log("Is Local:", addr.isLocal); // false
console.log("Has Punycode:", addr.hasPunycode); // false

// Parse from URL
const url = new URL("https://example.com/path");
const urlAddr = Address.loadFromTarget(url);
console.log("From URL:", urlAddr.hostname); // example.com

// IP address validation
const Addr_01 = new Address("192.168.1.1");
console.log("Is Local IP:", Addr_01.isLocal); // true

const Addr_02 = new Address("8.8.8.8");
console.log("Is Local IP:", Addr_02.isLocal); // false
`

API

$3

#### Constructor Options

`ts
interface DomainCheckerOptions {
server?: string[]; // Custom DNS servers
dkimSelector?: string; // Default: 'default'
useCache?: boolean; // Enable DNS caching
cacheTTL?: number; // Cache TTL in ms
smtpTimeout?: number; // Default: 10000
dnsTimeout?: number; // Default: 5000
httpTimeout?: number; // Default: 8000
socketIdleTimeout?: number; // RFC 5321 socket idle timeout
useDomainNS?: boolean; // Query domain's authoritative nameservers (Default: false)
useMtaSts?: boolean; // Enable MTA-STS related lookups (Default: false)
ignoreIPv6?: boolean; // Ignore IPv6 addresses
tries?: number; // Default: 3
failoverServers?: string[][]; // Default: [['1.1.1.1','1.0.0.1'], ['8.8.8.8','8.8.4.4']]
blockLocalIPs?: boolean; // Block local/private IPs (Default: false)
deliveryPort?: number; // Default: 25
}
`

#### Methods

- hasMxRecord(target: Target): Promise - Check if domain has MX records
- getMxRecord(options: ResolveOptions): Promise - Get MX records
- getSmtpConnection(target: Target): Promise - Test SMTP connection
- getTxtRecord(options: ResolveOptions): Promise - Get all TXT records parsed
- getSpfRecord(options: ResolveOptions): Promise - Get SPF record
- getDkimRecord(options: ResolveOptions): Promise - Get DKIM record
- getDmarcRecord(options: ResolveOptions): Promise - Get DMARC record
- getStsRecord(options: ResolveOptions): Promise - Get MTA-STS record
- getCustomRecords(options: ResolveOptions): Promise - Get custom TXT records
- getCustomKVRecord(options: ResolveOptions, key: string): Promise - Get specific key-value record
- getAllKVRecords(options: ResolveOptions): Promise - Get all key-value records
- getNameServers(target: Target): Promise - Get authoritative name servers

$3

#### Constructor

- new Address(mailOrHost: string) - Create new Address instance

`ts
import {Address } from "email-domain-check";
const addr_01 = new Address('user@gmail.com'); // string email or domain
const addr_02 = new Address('gmail.com');

`

#### Static Constructor Method

- Address.loadFromTarget(target: string | URL | Address): Address - Parse email/domain/URL

#### Properties

- source: string - Original input
- hostname: string - Domain name or IP
- user?: string - Email local part (if email)
- ipKind: IPKind - IP type (None, IPv4, IPv6)
- isIP: boolean - Is an IP address
- isLocal: boolean - Is local/private IP
- hasPunycode: boolean` - Contains punycode