Email Provider Links

Generate direct login links for any email address across 93+ providers (Gmail, Outlook, Yahoo, etc.) to streamline user authentication flows.

A robust TypeScript library providing direct links to 93 email providers (180 domains) with concurrent DNS resolution, optimized performance, comprehensive email validation, and advanced security features for login and password reset flows.

🚀 Try it out

Live Demo - Test the library with any email address and see it in action!

✨ New in Version 4.0.0

Major Performance & Security Release - Full backward compatibility maintained

• 🚀 Performance Revolution: Achieved 100,000+ operations/second throughput with sub-millisecond response times
• ⚡ Lightning Performance: Domain lookups in ~0.07ms, cached access in ~0.003ms
• 🛡️ Zero-Trust Architecture: Runtime data validation with cryptographic integrity verification
• 🔒 Enhanced Security: SHA-256 hash verification and supply chain protection
• 🎯 Rigorous Testing: 445 comprehensive tests with enhanced performance validation
• 📊 Extreme Optimization: 99.9% cache hit rate and ultra-low memory footprint
• 🧪 Quality Assurance: 94.65% code coverage with stress testing under enterprise loads
• 🔄 Seamless Upgrade: All existing APIs remain fully compatible

✨ Core Features

• 🚀 Fast & Lightweight: Zero dependencies, ultra-low memory (0.10MB initial, 0.00004MB per 1000 ops), small footprint (~39.5KB compressed)
• 📧 93 Email Providers: Gmail, Outlook, Yahoo, ProtonMail, iCloud, and many more
• 🌐 207 Domains Supported: Comprehensive international coverage
• 🌍 Full IDN Support: International domain names with RFC compliance and Punycode
• ✅ Advanced Email Validation: International email validation with detailed error reporting
• 🏢 Business Domain Detection: DNS-based detection for custom domains (Google Workspace, Microsoft 365, etc.)
• 🔒 Built-in Security: Multi-layer protection with cryptographic hash verification, URL validation, and supply chain attack prevention
• 🛡️ Zero-Trust Architecture: All provider data undergoes integrity verification - no insecure fallbacks
• 🔐 HTTPS-Only: Strict HTTPS enforcement with domain allowlisting and malicious pattern detection
• 📝 Type Safe: Full TypeScript support with comprehensive interfaces
• ⚡ Performance Optimized: Smart DNS fallback with configurable timeouts
• 🚦 Rate Limiting: Built-in DNS query rate limiting to prevent abuse
• 🔄 Email Alias Detection: Normalize Gmail dots, plus addressing, and provider-specific aliases
• 🛡️ Fraud Prevention: Detect duplicate accounts through email alias manipulation
• 📦 Batch Processing: Efficiently process multiple emails with deduplication
• 🧪 Thoroughly Tested: 445 tests with 94.65% code coverage

Installation

Using npm:

npm install @mikkelscheike/email-provider-links

Requirements

• Node.js: >=18.0.0 (Tested on 18.x, 20.x, 22.x, 24.x)
• TypeScript: >=4.0.0 (optional, but recommended)
• Zero runtime dependencies - No external packages required

Node.js 24 Support ✨

Fully compatible with the latest Node.js 24.x! The library is tested on:

• Node.js 18.x (LTS)
• Node.js 20.x (LTS)
• Node.js 22.x (Current)
• Node.js 24.x (Latest) - Full support with latest features

Supported Providers

📊 Current Coverage: 93 providers supporting 207 domains

Consumer Email Providers:

• Gmail (2 domains): gmail.com, googlemail.com
• Microsoft Outlook (15 domains): outlook.com, hotmail.com, live.com, msn.com, and 11 more
• Yahoo Mail (19 domains): yahoo.com, yahoo.co.uk, yahoo.fr, ymail.com, rocketmail.com, and 14 more
• ProtonMail (4 domains): proton.me, protonmail.com, protonmail.ch, pm.me
• iCloud Mail (3 domains): icloud.com, me.com, mac.com
• Tutanota (6 domains): tutanota.com, tutanota.de, tutamail.com, tuta.io, keemail.me, tuta.com
• SimpleLogin (10 domains): simplelogin.io, 8alias.com, aleeas.com, slmail.me, and 6 more
• FastMail, Zoho Mail, AOL Mail, GMX, Web.de, Mail.ru, QQ Mail, NetEase, Yandex, and many more

Business Email (via DNS detection):

• Microsoft 365 (Business domains via MX/TXT records)
• Google Workspace (Custom domains via DNS patterns)
• Amazon WorkMail (AWS email infrastructure via awsapps.com patterns)
• Zoho Workplace, FastMail Business, GoDaddy Email, Bluehost Email
• ProtonMail Business, Rackspace Email, IONOS, and others

Security & Privacy Focused:

• ProtonMail, Tutanota, Hushmail, CounterMail, Posteo
• Mailfence, SimpleLogin, AnonAddy

International Providers:

• Europe: GMX, Web.de, Orange, Free.fr, T-Online, Libero, Virgilio, Telekom, Tiscali, Skynet, Telenet, Xs4All, Planet.nl, Bluewin, Eircom
• Asia: QQ Mail, NetEase, Sina Mail, Alibaba Mail, Rakuten, Nifty, Naver (Korea), Daum (Korea), Biglobe (Japan), Sify, IndiatTimes (India)
• Eastern Europe: Centrum (Czech/Slovak), Interia, Onet (Poland), Rambler (Russia)
• Other Regions: UOL, Terra (Brazil), Telkom (South Africa), Xtra (New Zealand)

API Reference

Core Functions

getEmailProvider(email, timeout?)

Recommended - Complete provider detection with business domain support.

// Known providers (instant response)
const result1 = await getEmailProvider('user@gmail.com');
// Returns: { provider: "Gmail", loginUrl: "https://mail.google.com/mail/" }

// Business domains (DNS lookup with timeout)
const result2 = await getEmailProvider('user@company.com', 2000);
// Returns: { provider: "Google Workspace", detectionMethod: "mx_record" }

getEmailProviderSync(email)

Fast - Instant checks for known providers (no DNS lookup).

const result = getEmailProviderSync('user@outlook.com');
// Returns: { provider: "Outlook", loginUrl: "https://outlook.live.com/" }

Email Alias Support

The library handles provider-specific email alias rules:

// Gmail ignores dots and plus addressing
emailsMatch('user.name+work@gmail.com', 'username@gmail.com') // true

// Outlook preserves dots but ignores plus addressing
emailsMatch('user.name+work@outlook.com', 'username@outlook.com') // false

// Normalize emails to canonical form
const canonical = normalizeEmail('u.s.e.r+tag@gmail.com');
console.log(canonical); // 'user@gmail.com'

Provider Rules Overview:

• Gmail: Ignores dots, supports plus addressing
• Outlook: Preserves dots, supports plus addressing
• Yahoo: Preserves dots, supports plus addressing
• ProtonMail: Preserves dots, supports plus addressing
• FastMail: Preserves dots, supports plus addressing
• AOL: Preserves everything except case

Real-World Example

async function handlePasswordReset(email: string) {
  // Validate email first
  const validation = validateEmailAddress(email);
  if (!validation.isValid) {
    throw new Error(`Invalid email: ${validation.error?.message}`);
  }

  // Get provider information
  const result = await getEmailProvider(validation.normalizedEmail);
  
  return {
    providerUrl: result.loginUrl,
    providerName: result.provider?.companyProvider || null,
    isSupported: result.provider !== null,
    detectionMethod: result.detectionMethod
  };
}

Configuration

// Custom DNS timeout (default: 5000ms)
const result = await getEmailProvider(email, 2000);

// Rate limiting configuration
import { Config } from '@mikkelscheike/email-provider-links';
console.log('Max requests:', Config.MAX_DNS_REQUESTS_PER_MINUTE); // 10
console.log('Default timeout:', Config.DEFAULT_DNS_TIMEOUT);       // 5000ms

Advanced Usage

import { getLibraryStats, getSupportedProviders } from '@mikkelscheike/email-provider-links';

const stats = getLibraryStats();
console.log(`Version ${stats.version} supports ${stats.providerCount} providers`);

const providers = getSupportedProviders();
console.log(`Total providers: ${providers.length}`);

import { 
  normalizeEmail, 
  emailsMatch 
} from '@mikkelscheike/email-provider-links';

// Prevent duplicate accounts
async function registerUser(email: string) {
  const canonical = normalizeEmail(email);
  const existingUser = await findUserByEmail(canonical);
  
  if (existingUser) {
    throw new Error('Email already registered');
  }
  
  await createUser({ email: canonical });
}

// Check if login email matches registration
const match = emailsMatch('user@gmail.com', 'u.s.e.r+work@gmail.com');
console.log(match); // true - same person

// Simple normalization
const canonical = normalizeEmail('u.s.e.r+work@gmail.com');
console.log(canonical);  // 'user@gmail.com'

import { isEmailProviderSupported, extractDomain } from '@mikkelscheike/email-provider-links';

// Check if provider is supported
const supported = isEmailProviderSupported('user@gmail.com');

// Extract domain safely
const domain = extractDomain('USER@EXAMPLE.COM');
console.log(domain); // 'example.com'

Performance and Detection System

Development Mode Features

When NODE_ENV is set to 'development', the library provides additional insights:

// Memory usage is automatically logged:
// 🚀 Current memory usage: 0.08 MB

Performance Benchmarks

Extensively optimized for both speed and memory efficiency:

Speed Metrics:

• Initial provider load: ~0.5ms
• Known provider lookup: <1ms
• DNS-based detection: ~10ms average
• Batch processing: 1000 operations in ~1.1ms
• Email validation: <1ms for complex IDN domains

Memory Management:

• Initial load: ~0.10MB heap usage
• Batch operations: ~0.00004MB per 1000 operations
• Maximum load: < 25MB under heavy concurrent operations
• Cache efficiency: >99% hit rate
• Garbage collection: Automatic optimization

Real-World Performance:

• 50,000+ operations/second for known providers
• 100 concurrent DNS lookups in <1 second
• Average latency: <1ms for cached lookups
• Maximum latency: <25ms per lookup

To run benchmarks:

# Memory usage benchmark
npm run benchmark:memory

# DNS performance benchmark
npm run benchmark:dns

# Both scripts are available in the scripts/ directory
# and can be modified for custom performance testing

Contributing

We welcome contributions! See CONTRIBUTING.md for guidelines on adding new email providers.

Quality Assurance: This project maintains high standards with 445 comprehensive tests achieving 94.65% code coverage (95.95% function coverage).

Security: All provider data is protected by cryptographic hash verification, URL validation, and strict security controls. The library uses a zero-trust architecture with no insecure fallbacks - ensuring all data is verified before use.

Security

For security concerns or to report vulnerabilities, see our Security Policy.

License

MIT License - see LICENSE file for details.

Zero dependencies • TypeScript-first • Production ready • International support