@emailcheck/email-validator-js
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Advanced email validation with MX records, SMTP verification, disposable email detection, batch processing, and caching. Production-ready with TypeScript support.
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# Advanced Email Validator
[](https://npm.im/@emailcheck/email-validator-js)
[](https://github.com/email-check-app/email-validator-js/actions)
[](https://www.npmjs.com/package/@emailcheck/email-validator-js)
[](https://unpkg.com/browse/@emailcheck/email-validator-js@latest/)
[](https://www.typescriptlang.org/)
[](LICENSE.md)
š **Advanced email validation library** for Node.js with **MX record checking**, **SMTP verification**, **disposable email detection**, and **much more**. Now with **batch processing**, **advanced caching**, and **detailed error reporting**.
## š Table of Contents
- [Features](#features)
- [Use Cases](#use-cases)
- [API / Cloud Service](#api--cloud-hosted-service)
- [License](#license)
- [Installation](#installation)
- [Quick Start](#quick-start)
- [Migration Guide (to v3.x)](#migration-guide-to-v3x)
- [API Reference](#api-reference)
- [Configuration](#configuration-options)
- [Examples](#examples)
- [Command-line Tool (`email-validate`)](#-command-line-tool-email-validate)
- [Custom Cache Injection](#-custom-cache-injection)
- [Verification Transcript](#-verification-transcript)
- [Performance & Caching](#-performance--caching)
- [Email Provider Databases](#ļø-email-provider-databases)
- [Testing](#testing)
- [Contributing](#contributing)
## Features
- ā
RFC-5321-compliant format & TLD validation
- ā
MX record lookup with cache
- ā
Live SMTP probe with multi-port walk (25 ā 587 ā 465), TLS, custom step sequences
- ā
Disposable + free-provider detection (10k+ domains shipped as JSON)
- ā
Domain typo detection + suggestions (Levenshtein + curated typo map)
- ā
Name extraction from local-part with composite-name support
- ā
WHOIS-driven domain age and registration status
- ā
Pluggable cache (in-memory LRU, Redis, or your own backend)
- ā
**Verification transcript** ā opt-in structured per-step trace including the full SMTP wire-level transcript
- ā
**`parseSmtpError`** ā public utility to classify a free-form SMTP error string
- ā
Batch email verification with concurrency control + per-error classification
- ā
Serverless adapters for AWS Lambda, Vercel (Edge + Node), and Cloudflare Workers/Durable Objects
- ā
Strict TypeScript types ā zero `any` in `src/`
## Use Cases
- Increase delivery rate of email campaigns by removing spam emails
- Increase email open rate and your marketing IPs reputation
- Protect your website from spam, bots and fake emails
- Protect your product signup form from fake emails
- Protect your website forms from fake emails
- Protect your self from fraud orders and accounts using fake emails
- Integrate email address verification into your website forms
- Integrate email address verification into your backoffice administration and order processing
## API / Cloud Hosted Service
We offer this `email verification and validation and more advanced features` in our Scalable Cloud API Service Offering - You could try it here [Email Verification](https://email-check.app/products/email)
---
## License
email-validator-js is licensed under [Business Source License 1.1](LICENSE.md).
### Quick License Summary
| Use Case | Is a commercial license required?|
|----------|-----------|
| Exploring email-validator-js for your own research, hobbies, and testing purposes | **No** |
| Using email-validator-js to build a proof-of-concept application | **No** |
| Using email-validator-js to build revenue-generating applications | **Yes** |
| Using email-validator-js to build software that is provided as a service (SaaS) | **Yes** |
| Forking email-validator-js for any production purposes | **Yes** |
š **For commercial licensing**, visit [email-check.app/license/email-validator](https://email-check.app/license/email-validator) or contact us at [sales@email-check.app](mailto:sales@email-check.app?subject=Interested%20in%20email-validator-js%20commercial%20license).
---
## Installation
```bash
bun add @emailcheck/email-validator-js
# or
npm install @emailcheck/email-validator-js
# or
pnpm add @emailcheck/email-validator-js
```
### Requirements (consumers)
- Node.js >= 22 (currently-supported LTS lines: 22 Maintenance, 24 Active)
- TypeScript >= 4.0 (for TypeScript users)
### Requirements (contributing)
- Bun >= 1.3 (test runner, package manager, dev tooling)
- Node.js >= 24 only needed for `semantic-release` during the publish step
### Build System
- Rollup builds CJS + ESM bundles for the main package and the serverless entry
- `bun test` for the unit + mocked-IO suite (no jest, no ts-jest)
- Source data (common names, typo patterns, WHOIS servers) lives in `src/data/*.json`
## Quick Start
```typescript
import { verifyEmail } from '@emailcheck/email-validator-js';
// Basic usage
const result = await verifyEmail({
emailAddress: 'user@mydomain.com',
verifyMx: true,
verifySmtp: true,
smtpPerAttemptTimeoutMs: 3000, // bounds a single MX Ć port attempt
smtpTotalDeadlineMs: 8000, // bounds the entire SMTP probe (NEW in v5)
});
console.log(result.validFormat); // true
console.log(result.validMx); // true or false
console.log(result.validSmtp); // true or false
```
> **ā ļø Breaking Change in v3.x**: Enum values and constants now use `camelCase` instead of `SCREAMING_SNAKE_CASE`. See [Migration Guide](#migration-guide-to-v3x) for details.
## Migration Guide (to v3.x)
### Overview
Version 3.x introduces a **breaking change** to improve code consistency with TypeScript/JavaScript conventions. All enum values and constants now use `camelCase` instead of `SCREAMING_SNAKE_CASE`.
### What Changed
#### Enum Values
| Before (v2.x) | After (v3.x) |
|---------------|--------------|
| `EmailProvider.GMAIL` | `EmailProvider.gmail` |
| `EmailProvider.YAHOO` | `EmailProvider.yahoo` |
| `EmailProvider.HOTMAIL_B2C` | `EmailProvider.hotmailB2c` |
| `VerificationErrorCode.INVALID_FORMAT` | `VerificationErrorCode.invalidFormat` |
| `VerificationErrorCode.NO_MX_RECORDS` | `VerificationErrorCode.noMxRecords` |
| `SMTPStep.GREETING` | `SMTPStep.greeting` |
| `SMTPStep.EHLO` | `SMTPStep.ehlo` |
| `SMTPStep.MAIL_FROM` | `SMTPStep.mailFrom` |
#### Constants
| Before (v2.x) | After (v3.x) |
|---------------|--------------|
| `CHECK_IF_EMAIL_EXISTS_CONSTANTS.DEFAULT_TIMEOUT` | `checkIfEmailExistsConstants.defaultTimeout` |
| `CHECK_IF_EMAIL_EXISTS_CONSTANTS.GMAIL_DOMAINS` | `checkIfEmailExistsConstants.gmailDomains` |
| `WHOIS_SERVERS` | `whoisServers` |
### How to Migrate
#### Step 1: Update Enum References
```typescript
// Before
import { EmailProvider, VerificationErrorCode, SMTPStep } from '@emailcheck/email-validator-js';
if (provider === EmailProvider.GMAIL) { /* ... */ }
if (error === VerificationErrorCode.INVALID_FORMAT) { /* ... */ }
const steps = [SMTPStep.GREETING, SMTPStep.EHLO, SMTPStep.MAIL_FROM];
// After
import { EmailProvider, VerificationErrorCode, SMTPStep } from '@emailcheck/email-validator-js';
if (provider === EmailProvider.gmail) { /* ... */ }
if (error === VerificationErrorCode.invalidFormat) { /* ... */ }
const steps = [SMTPStep.greeting, SMTPStep.ehlo, SMTPStep.mailFrom];
```
#### Step 2: Update Constant References
```typescript
// Before
import { CHECK_IF_EMAIL_EXISTS_CONSTANTS } from '@emailcheck/email-validator-js';
const timeout = CHECK_IF_EMAIL_EXISTS_CONSTANTS.DEFAULT_TIMEOUT;
const domains = CHECK_IF_EMAIL_EXISTS_CONSTANTS.GMAIL_DOMAINS;
// After
import { checkIfEmailExistsConstants } from '@emailcheck/email-validator-js';
const timeout = checkIfEmailExistsConstants.defaultTimeout;
const domains = checkIfEmailExistsConstants.gmailDomains;
```
#### Step 3: Update Switch Statements
```typescript
// Before
switch (provider) {
case EmailProvider.YAHOO:
// Handle Yahoo
break;
case EmailProvider.HOTMAIL_B2C:
// Handle Hotmail
break;
}
// After
switch (provider) {
case EmailProvider.yahoo:
// Handle Yahoo
break;
case EmailProvider.hotmailB2c:
// Handle Hotmail
break;
}
```
### Important Notes
1. **String values remain unchanged**: The underlying string values (e.g., `'gmail'`, `'INVALID_FORMAT'`) are preserved. Only the property names changed.
2. **Runtime compatibility**: If you're comparing enum values to strings from external sources, the string values still work:
```typescript
// Still works in v3.x
if (provider === 'gmail') { /* ... */ }
```
3. **TypeScript strict mode**: Ensure you update all references before compiling, or TypeScript will report errors.
4. **Test your code**: After updating, run your test suite to ensure all enum and constant references are updated correctly.
### Automatic Migration
If you're using an IDE with refactoring support (like VS Code), you can use find-and-replace:
1. Find all references to old enum values
2. Replace with new camelCase versions
3. Run TypeScript compiler to verify no errors
### Need Help?
- š Check the [API Reference](#api-reference) for updated enum definitions
- š¬ [Open an issue](https://github.com/email-check-app/email-validator-js/issues) if you encounter problems
- š§ Contact [support@email-check.app](mailto:support@email-check.app)
## API Reference
### Core Functions
#### `verifyEmail(params: IVerifyEmailParams): Promise<VerificationResult>`
Comprehensive email verification with detailed results and error codes.
**Parameters:**
- `emailAddress` (string, required) ā Email address to verify.
- `verifyMx` (boolean) ā Resolve MX records (default: `true`).
- `verifySmtp` (boolean) ā Run live SMTP probe (default: `false`).
- `checkDisposable` (boolean) ā Disposable-provider list check (default: `true`).
- `checkFree` (boolean) ā Free-provider list check (default: `true`).
- `detectName` (boolean) ā Extract first/last name from local-part (default: `false`).
- `suggestDomain` (boolean) ā Suggest a corrected domain on typos (default: `true`).
- `checkDomainAge` (boolean) ā WHOIS creation-date lookup (default: `false`).
- `checkDomainRegistration` (boolean) ā WHOIS registration / expiry / lock lookup (default: `false`).
- `skipMxForDisposable` (boolean) ā Skip MX/SMTP for disposable addresses (default: `false`).
- `skipDomainWhoisForDisposable` (boolean) ā Skip WHOIS for disposable addresses (default: `false`).
- `smtpPort` (number) ā Force a specific port for the SMTP probe (overrides the `[25, 587, 465]` walk).
- **SMTP time-budget controls** (NEW in v5):
- `smtpPerAttemptTimeoutMs` (number) ā Per-MX Ć port budget in ms (default: `4000`).
- `smtpTotalDeadlineMs` (number) ā Hard cap on total wall-clock for the SMTP probe. Use this from a request handler with a tight latency budget. Default: unbounded.
- `smtpMaxConsecutiveFailures` (number) ā Bail after N connection-class failures in a row (`connection_error` / `connection_timeout` / `connection_closed`). Default: unbounded.
- `smtpMaxMxHosts` (number) ā Cap the MX walk to the first N hostnames. Default: unbounded.
- `smtpRetry` (`{ attempts, delayMs?, backoff? }`) ā Retry connection-class failures on the same MX Ć port. Default: no retries.
- `whoisTimeoutMs` (number) ā Per-WHOIS-query timeout (default: `5000`).
- `debug` (boolean) ā Per-line `console.debug` trace (default: `false`).
- `captureTranscript` (boolean) ā Populate `result.transcript` with a per-step structured trace (default: `false`).
- `nameDetectionMethod` (function) ā Override the default name-detection heuristic.
- `domainSuggestionMethod` (function) ā Override the default typo-suggestion heuristic.
- `commonDomains` (string[]) ā Custom canonical-domain list for the typo suggester.
- `cache` (Cache) ā Optional shared cache (MX, WHOIS, disposable / free, SMTP, domain results all stored).
**Returns:**
```typescript
{
email: string;
validFormat: boolean;
validMx: boolean | null;
validSmtp: boolean | null;
isDisposable: boolean;
isFree: boolean;
detectedName?: DetectedName | null;
domainAge?: DomainAgeInfo | null;
domainRegistration?: DomainRegistrationInfo | null;
domainSuggestion?: DomainSuggestion | null;
metadata?: {
verificationTime: number;
cached: boolean;
error?: VerificationErrorCode;
};
}
```
#### `verifyEmailBatch(params: IBatchVerifyParams): Promise<BatchVerificationResult>`
Verify multiple emails in parallel with concurrency control.
**Parameters:**
- `emailAddresses` (string[], required): Array of emails to verify
- `concurrency` (number): Parallel processing limit (default: 5)
- `detectName` (boolean): Detect names from email addresses
- `suggestDomain` (boolean): Enable domain typo suggestions
- Other parameters from `verifyEmail`
**Returns:**
```typescript
{
results: Map<string, VerificationResult>;
summary: {
total: number;
valid: number;
invalid: number;
errors: number;
processingTime: number;
};
}
```
### Name Detection Functions
#### `detectName(email: string): DetectedName | null`
Detect first and last name from email address.
```typescript
const name = detectName('john.doe@mydomain.com');
// Returns: { firstName: 'John', lastName: 'Doe', confidence: 0.9 }
```
**Detection Patterns:**
- Dot separator: `john.doe` ā John Doe (90% confidence)
- Underscore: `jane_smith` ā Jane Smith (80% confidence)
- Hyphen: `mary-johnson` ā Mary Johnson (80% confidence)
- CamelCase: `johnDoe` ā John Doe (70% confidence)
- **Composite names**: `mo1.test2` ā Mo1 Test2 (60% confidence)
- **Mixed alphanumeric**: `user1.admin2` ā User1 Admin2 (60% confidence)
- **Smart number handling**: `john.doe123` ā John Doe (80% confidence)
- **Contextual suffixes**: `john.doe.dev` ā John Doe (70% confidence)
- Single name: `alice` ā Alice (50% confidence)
**Enhanced Features:**
- Removes email aliases (text after +)
- Smart handling of numbers (preserves in composite names, removes trailing)
- Recognizes contextual suffixes (dev, company, sales, years)
- Handles complex multi-part names
- Proper name capitalization
- Filters out common non-name prefixes (admin, support, info, etc.)
#### `detectNameFromEmail(params: IDetectNameParams): DetectedName | null`
Advanced name detection with custom method support.
```typescript
const customMethod = (email: string) => {
// Your custom logic
return { firstName: 'Custom', lastName: 'Name', confidence: 1.0 };
};
const name = detectNameFromEmail({
email: 'user@mydomain.com',
customMethod: customMethod
});
```
**Parameters:**
- `email` (string): Email address
- `customMethod` (function): Custom detection logic
#### `defaultNameDetectionMethod(email: string): DetectedName | null`
The default name detection implementation, exported for custom extensions.
#### Algorithm-Specific Name Cleaning
##### `cleanNameForAlgorithm(name: string): string`
Clean a name by removing special characters (dots, underscores, asterisks). Specifically designed for Algorithm name processing.
```typescript
import { cleanNameForAlgorithm } from '@emailcheck/email-validator-js';
const cleanedName = cleanNameForAlgorithm('john.doe_smith*');
// Returns: 'johndoesmith'
const cleanedName2 = cleanNameForAlgorithm('first_name.last');
// Returns: 'firstnamelast'
```
##### `detectNameForAlgorithm(email: string): DetectedName | null`
Enhanced name detection for Algorithm with aggressive cleaning. Removes dots, underscores, and asterisks from detected names.
```typescript
import { detectNameForAlgorithm } from '@emailcheck/email-validator-js';
const result = detectNameForAlgorithm('john.doe_smith@company.com');
// Returns: { firstName: 'John', lastName: 'Doesmith', confidence: 0.9025 }
// Compared to regular detection:
import { detectName } from '@emailcheck/email-validator-js';
const normalResult = detectName('john.doe_smith@company.com');
// Returns: { firstName: 'John', lastName: 'Doe_smith', confidence: 0.95 }
```
**Key Differences:**
- Removes all dots (.), underscores (_), and asterisks (*) from detected names
- Slightly reduces confidence (95% of original) due to cleaning process
- Ideal for systems requiring clean, sanitized names without special characters
- Normalizes multiple spaces to single spaces
### Domain Suggestion Functions
#### `suggestEmailDomain(email: string, commonDomains?: string[]): DomainSuggestion | null`
Detect and suggest corrections for misspelled email domains.
```typescript
const suggestion = suggestEmailDomain('user@gmial.com');
// Returns: { original: 'user@gmial.com', suggested: 'user@gmail.com', confidence: 0.95 }
// With custom domain list
const customDomains = ['company.com', 'enterprise.org'];
const customSuggestion = suggestEmailDomain('user@compny.com', customDomains);
```
**Features:**
- 70+ common email domains by default
- String similarity algorithm
- Known typo patterns (95% confidence)
- Smart thresholds based on domain length
- 24-hour caching for performance
#### `suggestDomain(params: ISuggestDomainParams): DomainSuggestion | null`
Advanced domain suggestion with custom method support.
```typescript
const suggestion = suggestDomain({
domain: 'gmial.com',
customMethod: myCustomMethod,
commonDomains: ['company.com']
});
```
**Parameters:**
- `domain` (string): Domain to check
- `customMethod` (function): Custom suggestion logic
- `commonDomains` (string[]): Custom domain list
#### `defaultDomainSuggestionMethod(domain: string, commonDomains?: string[]): DomainSuggestion | null`
The default domain suggestion implementation, exported for custom extensions.
#### `isCommonDomain(domain: string, commonDomains?: string[]): boolean`
Check if a domain is in the common domains list.
```typescript
isCommonDomain('gmail.com'); // true
isCommonDomain('mycompany.com'); // false
// With custom list
isCommonDomain('mycompany.com', ['mycompany.com']); // true
```
#### `getDomainSimilarity(domain1: string, domain2: string): number`
Calculate similarity score between two domains (0-1).
```typescript
getDomainSimilarity('gmail.com', 'gmial.com'); // 0.8
getDomainSimilarity('gmail.com', 'yahoo.com'); // 0.3
```
### WHOIS Functions
> **Note:** WHOIS functions use PSL (Public Suffix List) validation to ensure domain validity before performing lookups. Invalid domains or domains without valid TLDs will return `null`.
#### `getDomainAge(domain: string, timeout?: number): Promise<DomainAgeInfo | null>`
Get domain age information via WHOIS lookup.
```typescript
const ageInfo = await getDomainAge('mydomain.com');
// Returns:
// {
// domain: 'mydomain.com',
// creationDate: Date,
// ageInDays: 7890,
// ageInYears: 21.6,
// expirationDate: Date,
// updatedDate: Date
// }
// Works with email addresses and URLs too
await getDomainAge('user@mydomain.com');
await getDomainAge('https://mydomain.com/path');
```
**Parameters:**
- `domain` (string): Domain, email, or URL to check
- `timeout` (number): Timeout in milliseconds (default: 5000)
**Returns:** `DomainAgeInfo` object or `null` if lookup fails
#### `getDomainRegistrationStatus(domain: string, timeout?: number): Promise<DomainRegistrationInfo | null>`
Get detailed domain registration status via WHOIS.
```typescript
const status = await getDomainRegistrationStatus('mydomain.com');
// Returns:
// {
// domain: 'mydomain.com',
// isRegistered: true,
// isAvailable: false,
// status: ['clientTransferProhibited'],
// registrar: 'Example Registrar',
// nameServers: ['ns1.mydomain.com', 'ns2.mydomain.com'],
// expirationDate: Date,
// isExpired: false,
// daysUntilExpiration: 365,
// isPendingDelete: false,
// isLocked: true
// }
```
**Parameters:**
- `domain` (string): Domain, email, or URL to check
- `timeout` (number): Timeout in milliseconds (default: 5000)
**Returns:** `DomainRegistrationInfo` object or `null` if lookup fails
**Features:**
- Supports 50+ TLDs with specific WHOIS servers
- Automatic WHOIS server discovery for unknown TLDs
- Parses various WHOIS response formats
- Uses PSL (Public Suffix List) for domain validation
- 1-hour result caching
- Extracts domain from emails and URLs
### Utility Functions
#### `isDisposableEmail(emailOrDomain: string, cache?: ICache, options?: { skipMxCheck?: boolean; skipDomain?: boolean }): boolean`
Check if email uses a disposable provider.
```typescript
// Basic usage
isDisposableEmail('user@tempmail.com'); // true
isDisposableEmail('tempmail.com'); // true
isDisposableEmail('gmail.com'); // false
// With options
isDisposableEmail('user@tempmail.com', null, {
skipMxCheck: true, // Skip MX record validation
skipDomain: true // Skip domain validation
}); // true
```
#### `isFreeEmail(emailOrDomain: string, cache?: ICache, options?: { skipMxCheck?: boolean; skipDomain?: boolean }): boolean`
Check if email uses a free provider.
```typescript
// Basic usage
isFreeEmail('user@gmail.com'); // true
isFreeEmail('yahoo.com'); // true
isFreeEmail('corporate.com'); // false
// With options
isFreeEmail('user@gmail.com', null, {
skipMxCheck: true, // Skip MX record validation
skipDomain: true // Skip domain validation
}); // true
```
#### `isValidEmail(emailAddress: string): boolean`
Validate email format (RFC 5321 compliant).
```typescript
isValidEmail('user@mydomain.com'); // true
isValidEmail('invalid.email'); // false
```
**Validation Rules:**
- Proper @ symbol placement
- Local part max 64 characters
- Domain max 253 characters
- No consecutive dots
- No leading/trailing dots
- Valid domain TLD
#### `isValidEmailDomain(emailOrDomain: string): boolean`
Validate if a domain has a valid TLD.
```typescript
isValidEmailDomain('mydomain.com'); // true
isValidEmailDomain('example.invalid'); // false
```
#### Cache Management
```typescript
import { getDefaultCache, clearDefaultCache, resetDefaultCache } from '@emailcheck/email-validator-js';
// Get the default cache instance (singleton)
const defaultCache = getDefaultCache();
// Clear all entries from the default cache
clearDefaultCache();
// Reset to a fresh cache instance
resetDefaultCache();
```
### Types and Interfaces
#### `DetectedName`
```typescript
interface DetectedName {
firstName?: string;
lastName?: string;
confidence: number; // 0-1 scale
}
```
#### `DomainSuggestion`
```typescript
interface DomainSuggestion {
original: string;
suggested: string;
confidence: number; // 0-1 scale
}
```
#### `NameDetectionMethod`
```typescript
type NameDetectionMethod = (email: string) => DetectedName | null;
```
#### `DomainSuggestionMethod`
```typescript
type DomainSuggestionMethod = (domain: string) => DomainSuggestion | null;
```
#### `DomainAgeInfo`
```typescript
interface DomainAgeInfo {
domain: string;
creationDate: Date;
ageInDays: number;
ageInYears: number;
expirationDate: Date | null;
updatedDate: Date | null;
}
```
#### `DomainRegistrationInfo`
```typescript
interface DomainRegistrationInfo {
domain: string;
isRegistered: boolean;
isAvailable: boolean;
status: string[];
registrar: string | null;
nameServers: string[];
expirationDate: Date | null;
isExpired: boolean;
daysUntilExpiration: number | null;
isPendingDelete?: boolean;
isLocked?: boolean;
}
```
### Constants
#### `COMMON_EMAIL_DOMAINS`
Array of 70+ common email domains used for typo detection.
```typescript
import { COMMON_EMAIL_DOMAINS } from '@emailcheck/email-validator-js';
console.log(COMMON_EMAIL_DOMAINS);
// ['gmail.com', 'yahoo.com', 'outlook.com', 'hotmail.com', ...]
```
**Includes:**
- Popular free providers (Gmail, Yahoo, Outlook, etc.)
- Business email services (Google Workspace, Microsoft, etc.)
- Privacy-focused providers (ProtonMail, Tutanota, etc.)
- Regional providers (GMX, Yandex, QQ, etc.)
- Hosting services (GoDaddy, Namecheap, etc.)
### Error Codes
```typescript
enum VerificationErrorCode {
invalidFormat = 'INVALID_FORMAT',
invalidDomain = 'INVALID_DOMAIN',
noMxRecords = 'NO_MX_RECORDS',
smtpConnectionFailed = 'SMTP_CONNECTION_FAILED',
smtpTimeout = 'SMTP_TIMEOUT',
mailboxNotFound = 'MAILBOX_NOT_FOUND',
mailboxFull = 'MAILBOX_FULL',
networkError = 'NETWORK_ERROR',
disposableEmail = 'DISPOSABLE_EMAIL',
freeEmailProvider = 'FREE_EMAIL_PROVIDER'
}
```
## Configuration Options
### `timeout`
Set a timeout in milliseconds for the smtp connection. Default: `4000`.
### `verifyMx`
Enable or disable domain checking. This is done in two steps:
1. Verify that the domain does indeed exist
2. Verify that the domain has valid MX records
Default: `false`.
### `verifySmtp`
Enable or disable mailbox checking. Only a few SMTP servers allow this, and even then whether it works depends on your IP's reputation with those servers. This library performs a best effort validation:
* It returns `null` for Yahoo addresses, for failed connections, for unknown SMTP errors
* It returns `true` for valid SMTP responses
* It returns `false` for SMTP errors specific to the address's formatting or mailbox existence
Default: `false`.
### `checkDisposable` (NEW)
Check if the email domain is a known disposable email provider. Default: `false`.
### `checkFree` (NEW)
Check if the email domain is a known free email provider. Default: `false`.
### `detailed` (NEW)
Return detailed verification results with error codes. Default: `false`.
### `retryAttempts` (NEW)
Number of retry attempts for transient failures. Default: `1`.
## Examples
### Basic Usage
```typescript
import { verifyEmail } from '@emailcheck/email-validator-js';
const result = await verifyEmail({
emailAddress: 'foo@email.com',
verifyMx: true,
verifySmtp: true,
smtpPerAttemptTimeoutMs: 3000,
});
console.log(result.validFormat); // true
console.log(result.validMx); // true
console.log(result.validSmtp); // true
```
### Detailed Verification (NEW)
```typescript
import { verifyEmail } from '@emailcheck/email-validator-js';
const result = await verifyEmail({
emailAddress: 'foo@email.com',
verifyMx: true,
verifySmtp: true,
checkDisposable: true,
checkFree: true
});
// result.validFormat: true
// result.validMx: true
// result.validSmtp: true
// result.isDisposable: false
// result.isFree: false
// result.metadata.verificationTime: 125
```
### Batch Verification (NEW)
```typescript
import { verifyEmailBatch } from '@emailcheck/email-validator-js';
const emails = ['user1@gmail.com', 'user2@mydomain.com', 'invalid@fake.com'];
const result = await verifyEmailBatch({
emailAddresses: emails,
concurrency: 5,
verifyMx: true,
checkDisposable: true,
checkFree: true
});
// result.summary.valid: 2
// result.summary.invalid: 1
// result.summary.processingTime: 234
```
### Enhanced SMTP Verification (NEW)
```typescript
import { verifyMailboxSMTP, getDefaultCache } from '@emailcheck/email-validator-js';
// Direct SMTP probe ā caller already has resolved MX records.
const { smtpResult, port, cached, portCached } = await verifyMailboxSMTP({
local: 'user',
domain: 'example.com',
mxRecords: ['mx.example.com'],
options: {
ports: [25, 587, 465], // Plain ā STARTTLS-able ā implicit-TLS
perAttemptTimeoutMs: 5000, // Per-MX Ć port budget (renamed from `timeout` in v5)
totalDeadlineMs: 12_000, // Hard cap on total wall-clock (NEW in v5)
maxConsecutiveFailures: 3, // Bail after N connection-class failures (NEW in v5)
cache: getDefaultCache(), // Per-isolate verdict + port cache
debug: false,
tlsConfig: { // Renamed from `tls` in v5
rejectUnauthorized: false,
minVersion: 'TLSv1.2',
},
heloHostname: 'your-domain.com', // EHLO/HELO identity (renamed from `hostname` in v5)
startTls: 'auto', // STARTTLS upgrade on plaintext ports (NEW in v5)
pipelining: 'auto', // Use SMTP PIPELINING when advertised
captureTranscript: false, // See "SMTP Transcript Capture" below
},
});
console.log(`SMTP result: ${smtpResult.isDeliverable} via port ${port}`);
console.log(`canConnectSmtp=${smtpResult.canConnectSmtp}, error=${smtpResult.error ?? 'none'}`);
```
### Configuration presets (NEW in v5)
Don't want to think about timeouts and retries? Pick a preset that matches your deployment shape:
```typescript
import { verifyEmail, VERIFY_EMAIL_PRESETS } from '@emailcheck/email-validator-js';
// Lambda / Vercel / Cloudflare-Workers handler
await verifyEmail({
emailAddress: 'alice@example.com',
verifySmtp: true,
...VERIFY_EMAIL_PRESETS.serverless,
});
// Long-running worker / dyno
await verifyEmail({ ..., ...VERIFY_EMAIL_PRESETS.dedicated });
// Bulk processing
await verifyEmail({ ..., ...VERIFY_EMAIL_PRESETS.batch });
// Form-autocomplete UX (sub-3s)
await verifyEmail({ ..., ...VERIFY_EMAIL_PRESETS.fast });
```
| Preset | Per-attempt | Total deadline | Max consecutive failures | Max MX | Retry |
| --- | --- | --- | --- | --- | --- |
| `serverless` | 2500 ms | **5 s** | 3 | 2 | none ā fail fast |
| `dedicated` | 5000 ms | 30 s | unbounded | unbounded | 1 retry, 500 ms exp backoff |
| `batch` | 10 000 ms | 60 s | unbounded | unbounded | 2 retries, 1 s exp backoff |
| `fast` | 1500 ms | **3 s** | 2 | **1** | none ā fail fast |
`SMTP_PRESETS` is a parallel set with the unprefixed field names for `verifyMailboxSMTP({ options })` callers ā same values, same shape.
You can spread + override:
```typescript
await verifyEmail({
emailAddress: 'alice@example.com',
...VERIFY_EMAIL_PRESETS.serverless,
smtpTotalDeadlineMs: 3000, // tighter than the preset's 5s
});
```
### Time-budget controls (NEW in v5)
The probe walks `mxRecords Ć ports` (worst-case 4 Ć 3 = 12 attempts at 3s each = 36s). Four orthogonal knobs let you bound that:
```typescript
import { verifyEmail, verifyMailboxSMTP } from '@emailcheck/email-validator-js';
await verifyEmail({
emailAddress: 'maria.hernandez+news@yahoo.com',
verifySmtp: true,
smtpPerAttemptTimeoutMs: 3000, // Bound a single MX Ć port attempt
smtpTotalDeadlineMs: 5000, // Hard cap on total wall-clock
smtpMaxConsecutiveFailures: 3, // Bail after 3 connection failures in a row
smtpMaxMxHosts: 2, // Try only the first 2 MXes
smtpRetry: { // Retry connection-class failures
attempts: 1,
delayMs: 200,
backoff: 'exponential', // or 'fixed'
},
});
// On verifyMailboxSMTP directly, the same knobs are unprefixed:
await verifyMailboxSMTP({
local: 'alice', domain: 'example.com', mxRecords: [...],
options: {
perAttemptTimeoutMs: 3000,
totalDeadlineMs: 5000,
maxConsecutiveFailures: 3,
maxMxHosts: 2,
retry: { attempts: 1, delayMs: 200, backoff: 'exponential' },
},
});
```
| Knob | Default | When to use |
| --- | --- | --- |
| `(smtp)PerAttemptTimeoutMs` | `4000` (verifyEmail) / `3000` (verifyMailboxSMTP) | Per-MX Ć port budget. Bound a single attempt. |
| `(smtp)TotalDeadlineMs` | unbounded | Hard wall-clock cap. Use from a request handler with a tight latency budget. |
| `(smtp)MaxConsecutiveFailures` | unbounded | Cut off probes when the network path is dead. Counter resets on any non-connection-class outcome. |
| `(smtp)MaxMxHosts` | unbounded | Cap the MX walk regardless of how many DNS returned. |
| `(smtp)Retry` | no retries | Retry connection-class failures on the same MX Ć port. Definitive answers (250 / 550 / 552) are never retried. |
`PerAttemptTimeout` and `TotalDeadline` are **orthogonal** ā use both when you have both a per-attempt SLO and a hard caller-side budget.
### Custom SMTP step sequence
Override the default `greeting ā EHLO ā MAIL FROM ā RCPT TO` walk for advanced cases:
```typescript
import { verifyMailboxSMTP, SMTPStep } from '@emailcheck/email-validator-js';
const { smtpResult } = await verifyMailboxSMTP({
local: 'user',
domain: 'example.com',
mxRecords: ['mx.example.com'],
options: {
sequence: {
steps: [SMTPStep.greeting, SMTPStep.helo, SMTPStep.mailFrom, SMTPStep.rcptTo],
from: '<noreply@yourdomain.com>', // Custom MAIL FROM payload
},
ports: [587, 465],
},
});
```
### SMTP Transcript Capture
Set `captureTranscript: true` to get the full server reply log and command sequence on the result. Useful for debugging delivery quirks or building admin UIs:
```typescript
import { verifyMailboxSMTP } from '@emailcheck/email-validator-js';
const { smtpResult } = await verifyMailboxSMTP({
local: 'user',
domain: 'example.com',
mxRecords: ['mx.example.com'],
options: { ports: [25, 587], perAttemptTimeoutMs: 5000, captureTranscript: true },
});
// Both arrays aggregate across every MX Ć port attempted, prefixed:
// "mx.example.com:25|s| 220 mx.example.com ESMTP"
// "25|c| EHLO localhost"
console.log(smtpResult.transcript);
console.log(smtpResult.commands);
```
For verification across the entire pipeline (syntax / disposable / free / MX / SMTP / WHOIS / name / suggestion), enable `captureTranscript` on `verifyEmail` to get a structured per-step trace ā see [Verification Transcript](#verification-transcript) below.
### Running Examples
Examples are grouped by topic under `examples/`. See [examples/README.md](./examples/README.md) for the full index.
```bash
# Bun runs TS directly ā no compilation step
bun run examples/smtp/usage.ts
bun run examples/smtp/enhanced.ts
bun run examples/cache/custom-memory.ts
bun run examples/high-level/advanced-usage.ts
bun run examples/integrations/algolia.ts
```
**After installation in your own project (Node 22+):**
```bash
node --experimental-strip-types examples/smtp/usage.ts
```
### Name Detection (ENHANCED)
```typescript
import { detectName, verifyEmail } from '@emailcheck/email-validator-js';
// Standalone name detection - now with composite name support
const name = detectName('john.doe@mydomain.com');
// name: { firstName: 'John', lastName: 'Doe', confidence: 0.9 }
// Handle alphanumeric composite names
const composite = detectName('mo1.test2@mydomain.com');
// composite: { firstName: 'Mo1', lastName: 'Test2', confidence: 0.6 }
// Smart handling of numbers and suffixes
const withNumbers = detectName('john.doe123@mydomain.com');
// withNumbers: { firstName: 'John', lastName: 'Doe', confidence: 0.8 }
const withSuffix = detectName('jane.smith.dev@mydomain.com');
// withSuffix: { firstName: 'Jane', lastName: 'Smith', confidence: 0.7 }
// Integrated with email verification
const result = await verifyEmail({
emailAddress: 'jane_smith@mydomain.com',
detectName: true
});
// result.detectedName: { firstName: 'Jane', lastName: 'Smith', confidence: 0.8 }
// Custom detection method
const customMethod = (email: string) => {
// Your custom logic here
return { firstName: 'Custom', lastName: 'Name', confidence: 1.0 };
};
const resultCustom = await verifyEmail({
emailAddress: 'user@mydomain.com',
detectName: true,
nameDetectionMethod: customMethod
});
```
### Domain Typo Detection (NEW)
```typescript
import { suggestEmailDomain, verifyEmail } from '@emailcheck/email-validator-js';
// Standalone domain suggestion
const suggestion = suggestEmailDomain('user@gmial.com');
// suggestion: { original: 'user@gmial.com', suggested: 'user@gmail.com', confidence: 0.95 }
// Integrated with email verification (enabled by default in detailed mode)
const result = await verifyEmail({
emailAddress: 'john@yaho.com',
suggestDomain: true // Default: true for detailed verification
});
// result.domainSuggestion: { original: 'john@yaho.com', suggested: 'john@yahoo.com', confidence: 0.9 }
// With custom domain list
const customDomains = ['company.com', 'enterprise.org'];
const resultCustom = await verifyEmail({
emailAddress: 'user@compny.com',
suggestDomain: true,
commonDomains: customDomains
});
// resultCustom.domainSuggestion: { suggested: 'user@company.com', confidence: 0.85 }
```
### Handling Different Validation Scenarios
When a domain does not exist or has no MX records:
```typescript
const result = await verifyEmail({
emailAddress: 'foo@bad-domain.com',
verifyMx: true,
verifySmtp: true
});
// result.validFormat: true (format is valid)
// result.validMx: false (no MX records)
// result.validSmtp: null (couldn't be performed)
```
### Using Detailed Verification for Better Insights
```typescript
const result = await verifyEmail({
emailAddress: 'user@suspicious-domain.com',
verifyMx: true,
verifySmtp: true,
checkDisposable: true,
checkFree: true
});
if (!result.validFormat) {
console.log('Invalid email format');
} else if (!result.validMx) {
console.log('Invalid domain - no MX records');
} else if (result.isDisposable) {
console.log('Disposable email detected');
} else if (result.metadata?.error) {
switch (result.metadata.error) {
case VerificationErrorCode.disposableEmail:
console.log('Rejected: Disposable email');
break;
case VerificationErrorCode.noMxRecords:
console.log('Rejected: Invalid domain');
break;
case VerificationErrorCode.mailboxNotFound:
console.log('Rejected: Mailbox does not exist');
break;
}
}
```
### Batch Processing for Large Lists
```typescript
const emails = [
'valid@gmail.com',
'test@tempmail.com',
'user@company.com',
// ... hundreds more
];
const batch = await verifyEmailBatch({
emailAddresses: emails,
concurrency: 10, // Process 10 emails simultaneously
verifyMx: true,
checkDisposable: true,
detailed: true
});
console.log(`Processed ${batch.summary.total} emails`);
console.log(`Valid: ${batch.summary.valid}`);
console.log(`Invalid: ${batch.summary.invalid}`);
console.log(`Time: ${batch.summary.processingTime}ms`);
// Filter out invalid emails
const validEmails = [];
for (const [email, result] of batch.results) {
if (result.validFormat) {
validEmails.push(email);
}
}
```
### Performance Optimization with Caching
```typescript
// First verification - hits DNS and SMTP
const first = await verifyEmail({
emailAddress: 'cached@mydomain.com',
verifyMx: true
});
// Takes ~500ms
// Second verification - uses cache
const second = await verifyEmail({
emailAddress: 'cached@mydomain.com',
verifyMx: true
});
// Takes ~1ms (cached)
// Clear cache if needed
clearAllCaches();
```
## š» Command-line Tool (`email-validate`)
`bun add -g @emailcheck/email-validator-js` (or the npm equivalent) installs an
`email-validate` binary. It runs the full validation pipeline against one
address, captures a structured transcript, prints the result to stdout, and
saves the JSON result to `./logs/` by default.
```bash
# Quick interactive check ā full pipeline, pretty colored output
email-validate alice@example.com
# Skip the SMTP probe (fast, just format / MX / lists / typos)
email-validate alice@example.com --no-smtp
# Add WHOIS age + registration for full domain reputation picture
email-validate alice@example.com --whois-age --whois-registration
# Pipe JSON through jq
email-validate alice@example.com --format json --quiet --no-log-file | jq
# Use the exit code in shell scripts (0 = ok, 1 = undeliverable / invalid)
if email-validate "$EMAIL" --quiet --no-log-file > /dev/null; then
echo "good email"
fi
# Pin to a single SMTP port + custom HELO + custom log path
email-validate alice@example.com --port 587 --hostname mta.acme.com --log-dir /var/log/email
# Debug a delivery quirk ā full transcript + console logs
email-validate alice@example.com --debug --format pretty
```
### Defaults
The CLI uses **interactive-friendly defaults** different from the library
defaults (which favor speed over thoroughness for batch use):
| Flag | CLI default | Library default |
| ------------------------- | ----------- | --------------- |
| `--smtp` | **on** | off |
| `--detect-name` | **on** | off |
| `--whois-age` / `--whois-registration` | off | off |
| `--captureTranscript` | **on** | off |
| `--log-dir` | `./logs` | n/a |
The default config writes a JSON result to `./logs/email-validate-<timestamp>-<email>.json` after every run.
### Programmatic CLI
The CLI parser, formatter, and runner are also exported as a module so you can
embed `email-validate` semantics in your own tooling:
```typescript
import { parseArgs, run } from '@emailcheck/email-validator-js/cli';
const parsed = parseArgs(['user@example.com', '--no-smtp', '--format', 'json']);
if (parsed.kind === 'args') {
const exitCode = await run(parsed);
process.exit(exitCode);
}
```
Run `email-validate --help` to see every flag, or read
[examples/cli-usage.md](./examples/cli-usage.md) for end-to-end recipes.
## š Custom Cache Injection
The library supports parameter-based cache injection, allowing you to use custom cache backends like Redis, Memcached, or any LRU-compatible cache implementation.
### š¦ Performance & Caching
The library includes a built-in LRU cache for all operations. By default, it uses a lazy-loaded singleton cache instance.
#### Default Cache Usage
```typescript
import { verifyEmail } from '@emailcheck/email-validator-js';
// No cache setup needed - uses default LRU cache automatically
const result = await verifyEmail({
emailAddress: 'user@example.com',
verifyMx: true,
verifySmtp: true
});
// Subsequent calls with the same email will use cached results
const result2 = await verifyEmail({
emailAddress: 'user@example.com',
verifyMx: true,
verifySmtp: true
});
```
#### Custom Cache Implementation
Create your own cache by implementing the `ICache` interface:
```typescript
import { verifyEmail, type ICache, ICacheStore, DEFAULT_CACHE_OPTIONS } from '@emailcheck/email-validator-js';
import { LRUAdapter } from '@emailcheck/email-validator-js';
// Create custom cache with LRU adapters
const customCache: ICache = {
mx: new LRUAdapter<string[]>(DEFAULT_CACHE_OPTIONS.maxSize.mx, DEFAULT_CACHE_OPTIONS.ttl.mx),
disposable: new LRUAdapter<boolean>(DEFAULT_CACHE_OPTIONS.maxSize.disposable, DEFAULT_CACHE_OPTIONS.ttl.disposable),
free: new LRUAdapter<boolean>(DEFAULT_CACHE_OPTIONS.maxSize.free, DEFAULT_CACHE_OPTIONS.ttl.free),
domainValid: new LRUAdapter<boolean>(DEFAULT_CACHE_OPTIONS.maxSize.domainValid, DEFAULT_CACHE_OPTIONS.ttl.domainValid),
smtp: new LRUAdapter<boolean | null>(DEFAULT_CACHE_OPTIONS.maxSize.smtp, DEFAULT_CACHE_OPTIONS.ttl.smtp),
domainSuggestion: new LRUAdapter<{ suggested: string; confidence: number } | null>(
DEFAULT_CACHE_OPTIONS.maxSize.domainSuggestion,
DEFAULT_CACHE_OPTIONS.ttl.domainSuggestion
),
whois: new LRUAdapter<any>(DEFAULT_CACHE_OPTIONS.maxSize.whois, DEFAULT_CACHE_OPTIONS.ttl.whois),
};
// Use with email verification
const result = await verifyEmail({
emailAddress: 'user@mydomain.com',
verifyMx: true,
verifySmtp: true,
cache: customCache // Pass the cache instance
});
```
#### Redis Cache Implementation
```typescript
import { verifyEmail, type ICache, ICacheStore } from '@emailcheck/email-validator-js';
import { RedisAdapter } from '@emailcheck/email-validator-js';
import Redis from 'ioredis';
// Create Redis client
const redis = new Redis({
host: 'localhost',
port: 6379,
});
// Create Redis cache
const redisCache: ICache = {
mx: new RedisAdapter(redis, {
keyPrefix: 'email:mx:',
ttl: 1800000, // 30 minutes
}),
disposable: new RedisAdapter(redis, {
keyPrefix: 'email:disposable:',
ttl: 86400000, // 24 hours
}),
free: new RedisAdapter(redis, {
keyPrefix: 'email:free:',
ttl: 86400000, // 24 hours
}),
domainValid: new RedisAdapter(redis, {
keyPrefix: 'email:domain:',
ttl: 86400000, // 24 hours
}),
smtp: new RedisAdapter(redis, {
keyPrefix: 'email:smtp:',
ttl: 1800000, // 30 minutes
}),
domainSuggestion: new RedisAdapter(redis, {
keyPrefix: 'email:suggest:',
ttl: 86400000, // 24 hours
}),
whois: new RedisAdapter(redis, {
keyPrefix: 'email:whois:',
ttl: 3600000, // 1 hour
}),
};
// Use with batch verification
import { verifyEmailBatch } from '@emailcheck/email-validator-js';
const batchResult = await verifyEmailBatch({
emailAddresses: ['user1@mydomain.com', 'user2@mydomain.com'],
verifyMx: true,
verifySmtp: true,
cache: redisCache,
concurrency: 10
});
```
#### Custom Cache Store Implementation
Create your own cache adapter by implementing the `ICacheStore` interface:
```typescript
import { verifyEmail, type ICacheStore } from '@emailcheck/email-validator-js';
class MyCustomCache<T> implements ICacheStore<T> {
private store = new Map<string, { value: T; expiry: number }>();
async get(key: string): Promise<T | null> {
const item = this.store.get(key);
if (!item) return null;
if (Date.now() > item.expiry) {
this.store.delete(key);
return null;
}
return item.value;
}
async set(key: string, value: T, ttlMs?: number): Promise<void> {
const expiry = Date.now() + (ttlMs || 3600000);
this.store.set(key, { value, expiry });
}
async delete(key: string): Promise<boolean> {
return this.store.delete(key);
}
async has(key: string): Promise<boolean> {
const item = this.store.get(key);
if (!item) return false;
if (Date.now() > item.expiry) {
this.store.delete(key);
return false;
}
return true;
}
async clear(): Promise<void> {
this.store.clear();
}
size(): number {
return this.store.size;
}
}
// Use custom cache store
const customCache = {
mx: new MyCustomCache<string[]>(),
disposable: new MyCustomCache<boolean>(),
free: new MyCustomCache<boolean>(),
domainValid: new MyCustomCache<boolean>(),
smtp: new MyCustomCache<boolean | null>(),
domainSuggestion: new MyCustomCache<{ suggested: string; confidence: number } | null>(),
whois: new MyCustomCache<any>(),
};
const result = await verifyEmail({
emailAddress: 'user@example.com',
cache: customCache
});
```
### Cache Options
Default cache TTL and size settings:
```typescript
import { DEFAULT_CACHE_OPTIONS } from '@emailcheck/email-validator-js';
// TTL (Time To Live) in milliseconds
DEFAULT_CACHE_OPTIONS.ttl = {
mx: 3600000, // 1 hour
disposable: 86400000, // 24 hours
free: 86400000, // 24 hours
domainValid: 86400000, // 24 hours
smtp: 1800000, // 30 minutes
domainSuggestion: 86400000, // 24 hours
whois: 3600000, // 1 hour
};
// Maximum number of entries per cache type
DEFAULT_CACHE_OPTIONS.maxSize = {
mx: 500,
disposable: 1000,
free: 1000,
domainValid: 1000,
smtp: 500,
domainSuggestion: 1000,
whois: 200,
};
```
## š Serverless Deployment
The package ships a serverless build (`@emailcheck/email-validator-js/serverless/*`) that runs without `node:net` / `node:dns` / `node:tls`. It targets:
- **AWS Lambda** ā API Gateway, direct invocation, routed handler
- **GCP Cloud Functions (2nd gen)** ā Express-style `(req, res)` on Cloud Run
- **Vercel** ā Edge Functions and Node.js runtime
- **Cloudflare Workers** ā including KV write-through and Durable Objects
- **Netlify Functions** ā Lambda-shaped event with redirect-aware path stripping
- **Azure Functions (v4 model)** ā Web-API-shaped HTTP triggers
- **Netlify Edge Functions / Deno Deploy** ā direct `validateEmailCore` use
### AWS Lambda (routed handler)
```typescript
// Routed: GET /health, POST /validate, POST /validate/batch
export { handler } from '@emailcheck/email-validator-js/serverless/aws';
```
Other shapes available: `apiGatewayHandler` (legacy, no path routing) and `lambdaHandler` (direct invocation).
### Vercel Edge Functions
```typescript
// app/api/validate/route.ts
import { handler } from '@emailcheck/email-validator-js/serverless/vercel';
export const runtime = 'edge';
export async function POST(request: Request) { return handler(request); }
```
Other shapes: `edgeHandler` (no routing) and `nodeHandler` (Express-style).
### Cloudflare Workers
```typescript
// src/worker.ts
export { default } from '@emailcheck/email-validator-js/serverless/cloudflare';
```
Bind a `EMAIL_CACHE` KV namespace in `wrangler.toml` to get write-through caching across instances. Bind `EMAIL_VALIDATOR` as a Durable Object (class `EmailValidatorDO`, also exported) for stateful validation with `/validate`, `/cache/clear`, `/cache/stats`.
### GCP Cloud Functions (2nd gen)
```typescript
import { gcpHandler } from '@emailcheck/email-validator-js/serverless/gcp';
export const validateEmail = gcpHandler;
```
Deploy with `gcloud functions deploy --gen2 --runtime=nodejs20 --trigger-http`. See [SERVERLESS.md](SERVERLESS.md#gcp-cloud-functions-2nd-gen) for the Functions Framework integration and Cloud Run usage.
### Netlify Functions
```typescript
// netlify/functions/validate.ts
export { netlifyHandler as handler } from '@emailcheck/email-validator-js/serverless/netlify';
```
The adapter strips `/.netlify/functions/<name>` and `/api/*` prefixes automatically, so the same handler works whether you hit the raw function URL or a redirect.
### Azure Functions (v4)
```typescript
import { app } from '@azure/functions';
import { azureHandler } from '@emailcheck/email-validator-js/serverless/azure';
app.http('validateEmail', {
methods: ['GET', 'POST', 'OPTIONS'],
route: '{*path}',
handler: azureHandler,
});
```
### Edge MX support via the built-in DoH resolver
A built-in `DoHResolver` ships with the package ā works in any runtime with `fetch` (Cloudflare Workers, Vercel Edge, Deno, browsers, Node 22+):
```typescript
import {
validateEmailCore,
DoHResolver,
} from '@emailcheck/email-validator-js/serverless/verifier';
const result = await validateEmailCore('alice@example.com', {
validateMx: true,
dnsResolver: new DoHResolver(), // defaults to Cloudflare 1.1.1