dcrouter/readme.example.md

DCRouter Email Configuration Example

This document provides a comprehensive example of configuring the UnifiedEmailServer in DCRouter for various email routing scenarios.

Basic Configuration

Here's a complete example of a email configuration for the UnifiedEmailServer:

import { IEmailConfig, EmailProcessingMode, IDomainRule } from './ts/config/email.config.js';

const emailConfig: IEmailConfig = {
  // Basic server settings
  useEmail: true,
  behindSmartProxy: false,
  hostname: "mail.example.com",
  ports: [25, 587, 465],
  
  // Default processing settings
  defaultMode: "forward" as EmailProcessingMode,
  defaultServer: "smtp.internal-relay.example.com",
  defaultPort: 25,
  defaultTls: true,
  
  // TLS configuration
  tls: {
    certPath: "/path/to/tls/certificate.pem",
    keyPath: "/path/to/tls/key.pem",
    caPath: "/path/to/tls/ca.pem",
    minVersion: "TLSv1.2",
    ciphers: "HIGH:!aNULL:!MD5:!RC4"
  },
  
  // Email size and connection limits
  maxMessageSize: 25 * 1024 * 1024, // 25MB
  
  // Authentication settings
  auth: {
    required: true,
    methods: ["PLAIN", "LOGIN"],
    users: [
      { username: "user1", password: "securepassword1" },
      { username: "user2", password: "securepassword2" }
    ]
  },
  
  // Domain routing rules
  domainRules: [
    // Process emails for your primary domain via MTA
    {
      pattern: "*@example.com",
      mode: "mta" as EmailProcessingMode,
      mtaOptions: {
        domain: "example.com",
        dkimSign: true,
        dkimOptions: {
          domainName: "example.com",
          keySelector: "mail"
        }
      }
    },
    
    // Forward support emails to help desk
    {
      pattern: "*@support.example.com",
      mode: "forward" as EmailProcessingMode,
      target: {
        server: "helpdesk.example.com",
        port: 25,
        useTls: true
      }
    },
    
    // Scan marketing emails for content and attachments
    {
      pattern: "*@marketing.example.com",
      mode: "process" as EmailProcessingMode,
      contentScanning: true,
      scanners: [
        {
          type: "attachment",
          action: "reject",
          blockedExtensions: [".exe", ".zip", ".js", ".vbs", ".bat"]
        },
        {
          type: "spam",
          threshold: 5.0,
          action: "tag"
        }
      ],
      transformations: [
        {
          type: "addHeader",
          header: "X-Scanned-By",
          value: "DCRouter Content Scanner"
        }
      ]
    },
    
    // Forward all other emails to a backup server
    {
      pattern: "*@*",
      mode: "forward" as EmailProcessingMode,
      target: {
        server: "backup-smtp.example.com",
        port: 587,
        useTls: true
      }
    }
  ],
  
  // Queue configuration
  queue: {
    storageType: "memory",
    ttl: 86400000, // 24 hours
    maxItems: 10000,
    checkInterval: 60000 // 1 minute
  },
  
  // Template configuration
  templateConfig: {
    from: "noreply@example.com",
    replyTo: "support@example.com",
    footerHtml: "<p>This is an automated message from Example Inc.</p>",
    footerText: "This is an automated message from Example Inc."
  },
  
  // IP warmup configuration
  serverConfig: {
    delivery: {
      concurrency: 10,
      rateLimit: {
        rate: 100,
        interval: 60000 // 1 minute
      },
      retries: {
        max: 3,
        delay: 300000, // 5 minutes
        useBackoff: true
      }
    },
    security: {
      useDkim: true,
      verifyDkim: true,
      verifySpf: true,
      verifyDmarc: true,
      enforceDmarc: true,
      useTls: true,
      requireValidCerts: true,
      securityLogLevel: "info",
      checkIPReputation: true,
      scanContent: true,
      maliciousContentAction: "tag",
      threatScoreThreshold: 7.0
    }
  }
};

Initializing the UnifiedEmailServer

Here's how to initialize the UnifiedEmailServer with the configuration:

import { UnifiedEmailServer, IUnifiedEmailServerOptions } from './ts/mail/routing/classes.unified.email.server.js';

// Convert EmailConfig to UnifiedEmailServerOptions
const serverOptions: IUnifiedEmailServerOptions = {
  ports: emailConfig.ports || [25],
  hostname: emailConfig.hostname || 'localhost',
  banner: `${emailConfig.hostname} ESMTP DCRouter`,
  
  // Authentication
  auth: emailConfig.auth,
  
  // TLS
  tls: emailConfig.tls,
  
  // Message limits
  maxMessageSize: emailConfig.maxMessageSize || 10 * 1024 * 1024, // 10MB default
  maxClients: 100,
  
  // Domain routing
  domainRules: emailConfig.domainRules || [],
  defaultMode: emailConfig.defaultMode || 'forward',
  defaultServer: emailConfig.defaultServer,
  defaultPort: emailConfig.defaultPort,
  defaultTls: emailConfig.defaultTls,
  
  // Deliverability options
  ipWarmupConfig: {
    enabled: true,
    ipAddresses: ['198.51.100.1', '198.51.100.2', '198.51.100.3'],
    targetDomains: ['gmail.com', 'yahoo.com', 'outlook.com'],
    allocationPolicy: 'balanced'
  },
  
  reputationMonitorConfig: {
    enabled: true,
    domains: ['example.com', 'marketing.example.com'],
    alertThresholds: {
      bounceRate: 0.05, // 5%
      complaintRate: 0.001 // 0.1%
    }
  }
};

// Create and start the server
const emailServer = new UnifiedEmailServer(serverOptions);
emailServer.start().then(() => {
  console.log('UnifiedEmailServer started successfully');
}).catch((error) => {
  console.error('Failed to start UnifiedEmailServer:', error);
});

Use Case Examples

1. Forwarding Email Gateway (SMTP Proxy)

Configure DCRouter to forward emails for specific domains to internal mail servers:

const forwardingRules: IDomainRule[] = [
  // Main corporate domain - forward to Exchange
  {
    pattern: "*@corp.example.com",
    mode: "forward" as EmailProcessingMode,
    target: {
      server: "exchange.internal",
      port: 25,
      useTls: true
    }
  },
  // Marketing domain - forward to Marketing mail server
  {
    pattern: "*@marketing.example.com",
    mode: "forward" as EmailProcessingMode,
    target: {
      server: "marketing-mail.internal",
      port: 25,
      useTls: false
    }
  }
];

2. Outbound MTA with DKIM Signing and IP Warmup

Configure DCRouter as an outbound mail transfer agent with DKIM signing and IP warmup:

// MTA configuration with DKIM signing
const mtaRule: IDomainRule = {
  pattern: "*@outbound.example.com",
  mode: "mta" as EmailProcessingMode,
  mtaOptions: {
    domain: "outbound.example.com",
    dkimSign: true,
    dkimOptions: {
      domainName: "outbound.example.com",
      keySelector: "mail2023"
    }
  }
};

// IP Warmup configuration
const ipWarmupConfig = {
  enabled: true,
  ipAddresses: ['203.0.113.1', '203.0.113.2'],
  targetDomains: ['gmail.com', 'yahoo.com', 'hotmail.com', 'aol.com'],
  allocationPolicy: 'progressive',
  fallbackPercentage: 20
};

3. Content Scanning and Security Gateway

Configure DCRouter to scan emails for malicious content and enforce security policies:

const securityRule: IDomainRule = {
  pattern: "*@*",
  mode: "process" as EmailProcessingMode,
  contentScanning: true,
  scanners: [
    // Scan for malicious attachments
    {
      type: "attachment",
      action: "reject",
      blockedExtensions: [".exe", ".dll", ".bat", ".vbs", ".js", ".cmd", ".scr", ".com", ".pif"]
    },
    // Scan for spam
    {
      type: "spam",
      threshold: 6.0,
      action: "tag"
    },
    // Scan for viruses
    {
      type: "virus",
      action: "reject"
    }
  ],
  transformations: [
    // Add scanning headers
    {
      type: "addHeader",
      header: "X-Security-Scanned",
      value: "DCRouter Security Gateway"
    }
  ]
};

// Configure security settings
const securityConfig = {
  useDkim: true,
  verifyDkim: true,
  verifySpf: true,
  verifyDmarc: true,
  enforceDmarc: true,
  checkIPReputation: true,
  scanContent: true,
  maliciousContentAction: "quarantine",
  threatScoreThreshold: 5.0,
  rejectHighRiskIPs: true,
  securityLogLevel: "warn"
};

4. Multi-Tenant Email Server

Configure DCRouter to handle emails for multiple domains with different processing rules:

const multiTenantRules: IDomainRule[] = [
  // Tenant 1: Process locally
  {
    pattern: "*@tenant1.example.org",
    mode: "mta" as EmailProcessingMode,
    mtaOptions: {
      domain: "tenant1.example.org",
      dkimSign: true,
      dkimOptions: {
        domainName: "tenant1.example.org",
        keySelector: "t1mail"
      }
    }
  },
  // Tenant 2: Forward to their server
  {
    pattern: "*@tenant2.example.org",
    mode: "forward" as EmailProcessingMode,
    target: {
      server: "mail.tenant2.com",
      port: 587,
      useTls: true
    }
  },
  // Tenant 3: Process with content scanning
  {
    pattern: "*@tenant3.example.org",
    mode: "process" as EmailProcessingMode,
    contentScanning: true,
    scanners: [
      {
        type: "attachment",
        action: "tag",
        blockedExtensions: [".zip", ".rar", ".7z"]
      }
    ]
  }
];

Using the Bounce Management System

DCRouter includes a sophisticated bounce management system. Here's how to use it:

// Get an instance of the UnifiedEmailServer
const emailServer = new UnifiedEmailServer(serverOptions);

// Check if an email is on the suppression list
const isSuppressed = emailServer.isEmailSuppressed('user@example.com');

// Get suppression information
const suppressionInfo = emailServer.getSuppressionInfo('user@example.com');
if (suppressionInfo) {
  console.log(`Suppressed due to: ${suppressionInfo.reason}`);
  console.log(`Suppressed since: ${new Date(suppressionInfo.timestamp)}`);
  if (suppressionInfo.expiresAt) {
    console.log(`Suppression expires: ${new Date(suppressionInfo.expiresAt)}`);
  } else {
    console.log('Suppression is permanent');
  }
}

// Add an email to the suppression list
emailServer.addToSuppressionList(
  'problem-user@example.com',
  'Manual suppression due to user request',
  Date.now() + (30 * 24 * 60 * 60 * 1000) // Expires in 30 days
);

// Remove an email from the suppression list
emailServer.removeFromSuppressionList('reactivated-user@example.com');

// Get all suppressed emails
const suppressionList = emailServer.getSuppressionList();
console.log(`There are ${suppressionList.length} suppressed email addresses`);

Using the IP Warmup System

DCRouter's IP warmup system helps gradually build sender reputation for new IP addresses:

// Add a new IP to warmup
emailServer.addIPToWarmup('198.51.100.4');

// Get warmup status for all IPs
const warmupStatus = emailServer.getIPWarmupStatus();
console.log('IP Warmup Status:', warmupStatus);

// Get warmup status for a specific IP
const specificIPStatus = emailServer.getIPWarmupStatus('198.51.100.1');
console.log(`Warmup day: ${specificIPStatus.day}`);
console.log(`Daily limit: ${specificIPStatus.dailyLimit}`);
console.log(`Emails sent today: ${specificIPStatus.sentToday}`);

// Update IP metrics based on feedback from mailbox providers
emailServer.updateIPWarmupMetrics('198.51.100.1', {
  openRate: 0.25, // 25% open rate
  bounceRate: 0.02, // 2% bounce rate
  complaintRate: 0.001 // 0.1% complaint rate
});

// Check if an IP can send more emails today
if (emailServer.canIPSendMoreToday('198.51.100.1')) {
  console.log('IP can send more emails today');
} else {
  console.log('IP has reached its daily sending limit');
}

// Change the IP allocation policy
emailServer.setIPAllocationPolicy('volume-based');

Sender Reputation Monitoring

Monitor and manage your domain reputation with these features:

// Add a domain to monitoring
emailServer.addDomainToMonitoring('newdomain.example.com');

// Get reputation data for a specific domain
const reputationData = emailServer.getDomainReputationData('example.com');
console.log(`Reputation score: ${reputationData.score}`);
console.log(`Bounce rate: ${reputationData.bounceRate}`);
console.log(`Complaint rate: ${reputationData.complaintRate}`);

// Get a summary of all domains
const summary = emailServer.getReputationSummary();
console.log('Domain reputation summary:', summary);

// Record a custom engagement event
emailServer.recordReputationEvent('example.com', {
  type: 'open',
  count: 15
});

Updating Configuration at Runtime

DCRouter allows updating configurations dynamically without restarting:

// Update domain rules
const newRules: IDomainRule[] = [
  // New rules here
];
emailServer.updateDomainRules(newRules);

// Update server options
emailServer.updateOptions({
  maxMessageSize: 50 * 1024 * 1024, // 50MB
  maxClients: 200,
  defaultServer: 'new-relay.example.com'
});

This example configuration covers a wide range of use cases from simple forwarding to advanced security scanning, IP warmup, and reputation management, showcasing DCRouter's versatility as an email routing and processing solution.