email-reachable

Verify email address reachability using SMTP protocol without sending emails.

Features

• SMTP Verification: Connects to mail servers and verifies mailbox existence
• Catch-All Detection: Identifies domains that accept all email addresses
• MX Record Lookup: Discovers and prioritizes mail servers
• Syntax Validation: RFC-compliant email syntax checking
• Disposable Domain Detection: Identifies temporary email providers
• No External Services: All verification done locally via SMTP

Installation

npm install email-reachable

CLI Usage

# Basic usage
npx email-reachable [email protected]

# JSON output
npx email-reachable [email protected] --json

# Debug mode
npx email-reachable [email protected] --debug

# Custom timeout
npx email-reachable [email protected] --timeout=15000

CLI Output

✓ [email protected]
  Reachable: true
  Reason: valid
  Syntax Valid: true
  Disposable: false
  Catch-All: false
  MX Records: mx1.example.com, mx2.example.com
  SMTP Response: 250 OK
  Duration: 1234ms

Exit Codes

• 0: Email is reachable
• 1: Email is not reachable or error occurred

Library Usage

import { verifyEmail } from 'email-reachable';

const result = await verifyEmail('[email protected]');

console.log(result);
// {
//   email: '[email protected]',
//   reachable: true,
//   reason: 'valid',
//   syntax: true,
//   disposable: false,
//   catchAll: false,
//   mxRecords: [{ exchange: 'mx1.example.com', priority: 10 }],
//   smtpResponse: { code: 250, message: 'OK', command: 'RCPT TO' },
//   duration: 1234
// }

Options

import { verifyEmail } from 'email-reachable';

const result = await verifyEmail('[email protected]', {
  timeout: 15000,           // Connection timeout in ms (default: 10000)
  senderDomain: 'mydomain.com',  // HELO domain (default: 'verify.local')
  senderAddress: '[email protected]',  // MAIL FROM address
  port: 25,                 // SMTP port (default: 25)
  debug: true,              // Enable debug output
});

Utility Functions

import {
  getMxRecords,
  extractDomain,
  extractLocalPart,
  isValidSyntax,
  isDisposableDomain,
} from 'email-reachable';

// Get MX records for a domain
const mxRecords = await getMxRecords('example.com');
// [{ exchange: 'mx1.example.com', priority: 10 }]

// Extract domain from email
const domain = extractDomain('[email protected]');
// 'example.com'

// Extract local part
const localPart = extractLocalPart('[email protected]');
// 'user'

// Validate syntax
const isValid = isValidSyntax('[email protected]');
// true

// Check for disposable domain
const isDisposable = isDisposableDomain('mailinator.com');
// true

Verification Result

| Field | Type | Description | |-------|------|-------------| | email | string | The email address that was verified | | reachable | boolean | Whether the email appears reachable | | reason | VerificationReason | Reason for the result | | syntax | boolean | Whether email syntax is valid | | disposable | boolean | Whether domain is a known disposable provider | | catchAll | boolean \| null | Whether domain accepts all addresses | | mxRecords | MxRecord[] | Discovered MX records | | smtpResponse | SmtpResponse | Last SMTP response received | | duration | number | Verification time in milliseconds |

Verification Reasons

| Reason | Description | |--------|-------------| | valid | Email appears valid and reachable | | invalid_syntax | Email address syntax is invalid | | no_mx_records | Domain has no MX records | | smtp_connection_failed | Could not connect to any mail server | | mailbox_not_found | Mail server rejected the recipient | | catch_all_domain | Domain accepts all addresses (can't verify) | | smtp_error | SMTP protocol error | | timeout | Connection or command timeout | | blocked | Mail server blocked verification attempt |

How It Works

1. Syntax Validation: Checks RFC-compliant email format
2. MX Lookup: Discovers mail servers via DNS
3. SMTP Connection: Connects to highest priority MX server
4. HELO/EHLO: Initiates SMTP conversation
5. MAIL FROM: Sets sender address
6. RCPT TO: Tests if recipient is accepted
7. Catch-All Detection: Tests random address to detect catch-all

Limitations

• Some mail servers may block verification attempts
• Catch-all domains can't have individual addresses verified
• Greylisting may cause false negatives
• Rate limiting may apply on some servers
• Port 25 may be blocked on some networks

Requirements

• Node.js >= 18.0.0
• Port 25 outbound access (SMTP)

License

MIT