update

test/suite/smtpclient_connection/test.ccm-01.basic-tcp-connection.ts

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+import { tap, expect } from '@git.zone/tstest/tapbundle';
+import { startTestServer, stopTestServer, type ITestServer } from '../../helpers/server.loader.js';
+import { createSmtpClient } from '../../../ts/mail/delivery/smtpclient/index.js';
+import type { SmtpClient } from '../../../ts/mail/delivery/smtpclient/smtp-client.js';
+
+let testServer: ITestServer;
+let smtpClient: SmtpClient;
+
+tap.test('setup - start SMTP server for basic connection test', async () => {
+  testServer = await startTestServer({
+    port: 2525,
+    tlsEnabled: false,
+    authRequired: false
+  });
+  
+  expect(testServer.port).toEqual(2525);
+});
+
+tap.test('CCM-01: Basic TCP Connection - should connect to SMTP server', async () => {
+  const startTime = Date.now();
+  
+  try {
+    // Create SMTP client
+    smtpClient = createSmtpClient({
+      host: testServer.hostname,
+      port: testServer.port,
+      secure: false,
+      connectionTimeout: 5000,
+      debug: true
+    });
+    
+    // Verify connection
+    const isConnected = await smtpClient.verify();
+    expect(isConnected).toBeTrue();
+    
+    const duration = Date.now() - startTime;
+    console.log(`✅ Basic TCP connection established in ${duration}ms`);
+    
+  } catch (error) {
+    const duration = Date.now() - startTime;
+    console.error(`❌ Basic TCP connection failed after ${duration}ms:`, error);
+    throw error;
+  }
+});
+
+tap.test('CCM-01: Basic TCP Connection - should report connection status', async () => {
+  expect(smtpClient.isConnected()).toBeTrue();
+  
+  const poolStatus = smtpClient.getPoolStatus();
+  console.log('📊 Connection pool status:', poolStatus);
+  
+  // For non-pooled connection, should have 1 connection
+  expect(poolStatus.total).toBeGreaterThanOrEqual(1);
+  expect(poolStatus.active).toBeGreaterThanOrEqual(0);
+});
+
+tap.test('CCM-01: Basic TCP Connection - should handle multiple connect/disconnect cycles', async () => {
+  // Close existing connection
+  await smtpClient.close();
+  expect(smtpClient.isConnected()).toBeFalse();
+  
+  // Create new client and test reconnection
+  for (let i = 0; i < 3; i++) {
+    const cycleClient = createSmtpClient({
+      host: testServer.hostname,
+      port: testServer.port,
+      secure: false,
+      connectionTimeout: 5000
+    });
+    
+    const isConnected = await cycleClient.verify();
+    expect(isConnected).toBeTrue();
+    
+    await cycleClient.close();
+    expect(cycleClient.isConnected()).toBeFalse();
+    
+    console.log(`✅ Connection cycle ${i + 1} completed`);
+  }
+});
+
+tap.test('CCM-01: Basic TCP Connection - should fail with invalid host', async () => {
+  let errorThrown = false;
+  
+  try {
+    const invalidClient = createSmtpClient({
+      host: 'invalid.host.that.does.not.exist',
+      port: 2525,
+      secure: false,
+      connectionTimeout: 3000
+    });
+    
+    await invalidClient.verify();
+  } catch (error) {
+    errorThrown = true;
+    expect(error).toBeInstanceOf(Error);
+    console.log('✅ Correctly failed to connect to invalid host');
+  }
+  
+  expect(errorThrown).toBeTrue();
+});
+
+tap.test('CCM-01: Basic TCP Connection - should timeout on unresponsive port', async () => {
+  let errorThrown = false;
+  const startTime = Date.now();
+  
+  try {
+    const timeoutClient = createSmtpClient({
+      host: testServer.hostname,
+      port: 9999, // Port that's not listening
+      secure: false,
+      connectionTimeout: 2000
+    });
+    
+    await timeoutClient.verify();
+  } catch (error) {
+    errorThrown = true;
+    const duration = Date.now() - startTime;
+    expect(error).toBeInstanceOf(Error);
+    expect(duration).toBeLessThan(3000); // Should timeout within 3 seconds
+    console.log(`✅ Connection timeout working correctly (${duration}ms)`);
+  }
+  
+  expect(errorThrown).toBeTrue();
+});
+
+tap.test('cleanup - close SMTP client', async () => {
+  if (smtpClient && smtpClient.isConnected()) {
+    await smtpClient.close();
+  }
+});
+
+tap.test('cleanup - stop SMTP server', async () => {
+  await stopTestServer(testServer);
+});
+
+tap.start();

test/suite/smtpclient_connection/test.ccm-02.tls-connection.ts

@@ -0,0 +1,162 @@
+import { tap, expect } from '@git.zone/tstest/tapbundle';
+import { startTestServer, stopTestServer, type ITestServer } from '../../helpers/server.loader.js';
+import { createSmtpClient } from '../../../ts/mail/delivery/smtpclient/index.js';
+import type { SmtpClient } from '../../../ts/mail/delivery/smtpclient/smtp-client.js';
+import { Email } from '../../../ts/mail/core/classes.email.js';
+
+let testServer: ITestServer;
+let smtpClient: SmtpClient;
+
+tap.test('setup - start SMTP server with TLS', async () => {
+  testServer = await startTestServer({
+    port: 2526,
+    tlsEnabled: true,
+    authRequired: false
+  });
+  
+  expect(testServer.port).toEqual(2526);
+  expect(testServer.config.tlsEnabled).toBeTrue();
+});
+
+tap.test('CCM-02: TLS Connection - should establish secure connection', async () => {
+  const startTime = Date.now();
+  
+  try {
+    // Create SMTP client with TLS
+    smtpClient = createSmtpClient({
+      host: testServer.hostname,
+      port: testServer.port,
+      secure: true,
+      connectionTimeout: 10000,
+      tls: {
+        rejectUnauthorized: false // For self-signed test certificates
+      },
+      debug: true
+    });
+    
+    // Verify secure connection
+    const isConnected = await smtpClient.verify();
+    expect(isConnected).toBeTrue();
+    
+    const duration = Date.now() - startTime;
+    console.log(`✅ TLS connection established in ${duration}ms`);
+    
+  } catch (error) {
+    const duration = Date.now() - startTime;
+    console.error(`❌ TLS connection failed after ${duration}ms:`, error);
+    throw error;
+  }
+});
+
+tap.test('CCM-02: TLS Connection - should send email over secure connection', async () => {
+  const email = new Email({
+    from: 'test@example.com',
+    to: 'recipient@example.com',
+    subject: 'TLS Connection Test',
+    text: 'This email was sent over a secure TLS connection',
+    html: '<p>This email was sent over a <strong>secure TLS connection</strong></p>'
+  });
+  
+  const result = await smtpClient.sendMail(email);
+  
+  expect(result.success).toBeTrue();
+  expect(result.acceptedRecipients).toContain('recipient@example.com');
+  expect(result.rejectedRecipients).toBeArray();
+  expect(result.rejectedRecipients.length).toEqual(0);
+  
+  console.log('✅ Email sent successfully over TLS');
+  console.log('📧 Message ID:', result.messageId);
+});
+
+tap.test('CCM-02: TLS Connection - should validate certificate options', async () => {
+  let errorThrown = false;
+  
+  try {
+    // Create client with strict certificate validation
+    const strictClient = createSmtpClient({
+      host: testServer.hostname,
+      port: testServer.port,
+      secure: true,
+      connectionTimeout: 5000,
+      tls: {
+        rejectUnauthorized: true, // Strict validation
+        servername: testServer.hostname
+      }
+    });
+    
+    await strictClient.verify();
+    await strictClient.close();
+  } catch (error) {
+    errorThrown = true;
+    // Expected to fail with self-signed certificate
+    expect(error).toBeInstanceOf(Error);
+    console.log('✅ Certificate validation working correctly');
+  }
+  
+  // For self-signed certs, strict validation should fail
+  expect(errorThrown).toBeTrue();
+});
+
+tap.test('CCM-02: TLS Connection - should support custom TLS options', async () => {
+  const tlsClient = createSmtpClient({
+    host: testServer.hostname,
+    port: testServer.port,
+    secure: true,
+    connectionTimeout: 10000,
+    tls: {
+      rejectUnauthorized: false,
+      minVersion: 'TLSv1.2',
+      maxVersion: 'TLSv1.3'
+    }
+  });
+  
+  const isConnected = await tlsClient.verify();
+  expect(isConnected).toBeTrue();
+  
+  await tlsClient.close();
+  console.log('✅ Custom TLS options accepted');
+});
+
+tap.test('CCM-02: TLS Connection - should handle TLS handshake errors', async () => {
+  // Start a non-TLS server to test handshake failure
+  const nonTlsServer = await startTestServer({
+    port: 2527,
+    tlsEnabled: false
+  });
+  
+  let errorThrown = false;
+  
+  try {
+    const failClient = createSmtpClient({
+      host: nonTlsServer.hostname,
+      port: nonTlsServer.port,
+      secure: true, // Try TLS on non-TLS server
+      connectionTimeout: 5000,
+      tls: {
+        rejectUnauthorized: false
+      }
+    });
+    
+    await failClient.verify();
+  } catch (error) {
+    errorThrown = true;
+    expect(error).toBeInstanceOf(Error);
+    console.log('✅ TLS handshake error handled correctly');
+  }
+  
+  expect(errorThrown).toBeTrue();
+  
+  await stopTestServer(nonTlsServer);
+});
+
+tap.test('cleanup - close SMTP client', async () => {
+  if (smtpClient && smtpClient.isConnected()) {
+    await smtpClient.close();
+  }
+});
+
+tap.test('cleanup - stop SMTP server', async () => {
+  await stopTestServer(testServer);
+});
+
+tap.start();

test/suite/smtpclient_connection/test.ccm-03.starttls-upgrade.ts

@@ -0,0 +1,200 @@
+import { tap, expect } from '@git.zone/tstest/tapbundle';
+import { startTestServer, stopTestServer, type ITestServer } from '../../helpers/server.loader.js';
+import { createSmtpClient } from '../../../ts/mail/delivery/smtpclient/index.js';
+import type { SmtpClient } from '../../../ts/mail/delivery/smtpclient/smtp-client.js';
+import { Email } from '../../../ts/mail/core/classes.email.js';
+
+let testServer: ITestServer;
+let smtpClient: SmtpClient;
+
+tap.test('setup - start SMTP server with STARTTLS support', async () => {
+  testServer = await startTestServer({
+    port: 2528,
+    tlsEnabled: true, // Enables STARTTLS capability
+    authRequired: false
+  });
+  
+  expect(testServer.port).toEqual(2528);
+});
+
+tap.test('CCM-03: STARTTLS Upgrade - should upgrade plain connection to TLS', async () => {
+  const startTime = Date.now();
+  
+  try {
+    // Create SMTP client starting with plain connection
+    smtpClient = createSmtpClient({
+      host: testServer.hostname,
+      port: testServer.port,
+      secure: false, // Start with plain connection
+      connectionTimeout: 10000,
+      tls: {
+        rejectUnauthorized: false // For self-signed test certificates
+      },
+      debug: true
+    });
+    
+    // The client should automatically upgrade to TLS via STARTTLS
+    const isConnected = await smtpClient.verify();
+    expect(isConnected).toBeTrue();
+    
+    const duration = Date.now() - startTime;
+    console.log(`✅ STARTTLS upgrade completed in ${duration}ms`);
+    
+  } catch (error) {
+    const duration = Date.now() - startTime;
+    console.error(`❌ STARTTLS upgrade failed after ${duration}ms:`, error);
+    throw error;
+  }
+});
+
+tap.test('CCM-03: STARTTLS Upgrade - should send email after upgrade', async () => {
+  const email = new Email({
+    from: 'test@example.com',
+    to: 'recipient@example.com',
+    subject: 'STARTTLS Upgrade Test',
+    text: 'This email was sent after STARTTLS upgrade',
+    html: '<p>This email was sent after <strong>STARTTLS upgrade</strong></p>'
+  });
+  
+  const result = await smtpClient.sendMail(email);
+  
+  expect(result.success).toBeTrue();
+  expect(result.acceptedRecipients).toContain('recipient@example.com');
+  expect(result.rejectedRecipients.length).toEqual(0);
+  
+  console.log('✅ Email sent successfully after STARTTLS upgrade');
+  console.log('📧 Message ID:', result.messageId);
+});
+
+tap.test('CCM-03: STARTTLS Upgrade - should handle servers without STARTTLS', async () => {
+  // Start a server without TLS support
+  const plainServer = await startTestServer({
+    port: 2529,
+    tlsEnabled: false // No STARTTLS support
+  });
+  
+  try {
+    const plainClient = createSmtpClient({
+      host: plainServer.hostname,
+      port: plainServer.port,
+      secure: false,
+      connectionTimeout: 5000,
+      debug: true
+    });
+    
+    // Should still connect but without TLS
+    const isConnected = await plainClient.verify();
+    expect(isConnected).toBeTrue();
+    
+    // Send test email over plain connection
+    const email = new Email({
+      from: 'test@example.com',
+      to: 'recipient@example.com',
+      subject: 'Plain Connection Test',
+      text: 'This email was sent over plain connection'
+    });
+    
+    const result = await plainClient.sendMail(email);
+    expect(result.success).toBeTrue();
+    
+    await plainClient.close();
+    console.log('✅ Successfully handled server without STARTTLS');
+    
+  } finally {
+    await stopTestServer(plainServer);
+  }
+});
+
+tap.test('CCM-03: STARTTLS Upgrade - should respect TLS options during upgrade', async () => {
+  const customTlsClient = createSmtpClient({
+    host: testServer.hostname,
+    port: testServer.port,
+    secure: false, // Start plain
+    connectionTimeout: 10000,
+    tls: {
+      rejectUnauthorized: false,
+      minVersion: 'TLSv1.2',
+      ciphers: 'HIGH:!aNULL:!MD5'
+    }
+  });
+  
+  const isConnected = await customTlsClient.verify();
+  expect(isConnected).toBeTrue();
+  
+  await customTlsClient.close();
+  console.log('✅ Custom TLS options applied during STARTTLS upgrade');
+});
+
+tap.test('CCM-03: STARTTLS Upgrade - should handle upgrade failures gracefully', async () => {
+  // Create a mock scenario where STARTTLS might fail
+  // This would typically happen with certificate issues or protocol mismatches
+  
+  let errorCaught = false;
+  
+  try {
+    const strictTlsClient = createSmtpClient({
+      host: testServer.hostname,
+      port: testServer.port,
+      secure: false,
+      connectionTimeout: 5000,
+      tls: {
+        rejectUnauthorized: true, // Strict validation with self-signed cert
+        servername: 'wrong.hostname.com' // Wrong hostname
+      }
+    });
+    
+    await strictTlsClient.verify();
+    await strictTlsClient.close();
+  } catch (error) {
+    errorCaught = true;
+    expect(error).toBeInstanceOf(Error);
+    console.log('✅ STARTTLS upgrade failure handled gracefully');
+  }
+  
+  // Should fail due to certificate validation
+  expect(errorCaught).toBeTrue();
+});
+
+tap.test('CCM-03: STARTTLS Upgrade - should maintain connection state after upgrade', async () => {
+  const stateClient = createSmtpClient({
+    host: testServer.hostname,
+    port: testServer.port,
+    secure: false,
+    connectionTimeout: 10000,
+    tls: {
+      rejectUnauthorized: false
+    }
+  });
+  
+  // Connect and verify
+  await stateClient.verify();
+  expect(stateClient.isConnected()).toBeTrue();
+  
+  // Send multiple emails to verify connection remains stable
+  for (let i = 0; i < 3; i++) {
+    const email = new Email({
+      from: 'test@example.com',
+      to: 'recipient@example.com',
+      subject: `STARTTLS State Test ${i + 1}`,
+      text: `Message ${i + 1} after STARTTLS upgrade`
+    });
+    
+    const result = await stateClient.sendMail(email);
+    expect(result.success).toBeTrue();
+  }
+  
+  await stateClient.close();
+  console.log('✅ Connection state maintained after STARTTLS upgrade');
+});
+
+tap.test('cleanup - close SMTP client', async () => {
+  if (smtpClient && smtpClient.isConnected()) {
+    await smtpClient.close();
+  }
+});
+
+tap.test('cleanup - stop SMTP server', async () => {
+  await stopTestServer(testServer);
+});
+
+tap.start();

test/suite/smtpclient_connection/test.ccm-04.connection-pooling.ts

@@ -0,0 +1,238 @@
+import { tap, expect } from '@git.zone/tstest/tapbundle';
+import { startTestServer, stopTestServer, type ITestServer } from '../../helpers/server.loader.js';
+import { createPooledSmtpClient } from '../../../ts/mail/delivery/smtpclient/index.js';
+import type { SmtpClient } from '../../../ts/mail/delivery/smtpclient/smtp-client.js';
+import { Email } from '../../../ts/mail/core/classes.email.js';
+
+let testServer: ITestServer;
+let pooledClient: SmtpClient;
+
+tap.test('setup - start SMTP server for pooling test', async () => {
+  testServer = await startTestServer({
+    port: 2530,
+    tlsEnabled: false,
+    authRequired: false,
+    maxConnections: 10
+  });
+  
+  expect(testServer.port).toEqual(2530);
+});
+
+tap.test('CCM-04: Connection Pooling - should create pooled client', async () => {
+  const startTime = Date.now();
+  
+  try {
+    // Create pooled SMTP client
+    pooledClient = createPooledSmtpClient({
+      host: testServer.hostname,
+      port: testServer.port,
+      secure: false,
+      maxConnections: 5,
+      maxMessages: 100,
+      connectionTimeout: 5000,
+      debug: true
+    });
+    
+    // Verify connection pool is working
+    const isConnected = await pooledClient.verify();
+    expect(isConnected).toBeTrue();
+    
+    const poolStatus = pooledClient.getPoolStatus();
+    console.log('📊 Initial pool status:', poolStatus);
+    expect(poolStatus.total).toBeGreaterThanOrEqual(0);
+    
+    const duration = Date.now() - startTime;
+    console.log(`✅ Connection pool created in ${duration}ms`);
+    
+  } catch (error) {
+    const duration = Date.now() - startTime;
+    console.error(`❌ Connection pool creation failed after ${duration}ms:`, error);
+    throw error;
+  }
+});
+
+tap.test('CCM-04: Connection Pooling - should handle concurrent connections', async () => {
+  // Send multiple emails concurrently
+  const emailPromises = [];
+  const concurrentCount = 5;
+  
+  for (let i = 0; i < concurrentCount; i++) {
+    const email = new Email({
+      from: 'test@example.com',
+      to: `recipient${i}@example.com`,
+      subject: `Concurrent Email ${i}`,
+      text: `This is concurrent email number ${i}`
+    });
+    
+    emailPromises.push(pooledClient.sendMail(email));
+  }
+  
+  // Wait for all emails to be sent
+  const results = await Promise.all(emailPromises);
+  
+  // Check all were successful
+  results.forEach((result, index) => {
+    expect(result.success).toBeTrue();
+    expect(result.acceptedRecipients).toContain(`recipient${index}@example.com`);
+  });
+  
+  // Check pool status after concurrent sends
+  const poolStatus = pooledClient.getPoolStatus();
+  console.log('📊 Pool status after concurrent sends:', poolStatus);
+  expect(poolStatus.total).toBeGreaterThanOrEqual(1);
+  expect(poolStatus.total).toBeLessThanOrEqual(5); // Should not exceed max
+  
+  console.log(`✅ Successfully sent ${concurrentCount} concurrent emails`);
+});
+
+tap.test('CCM-04: Connection Pooling - should reuse connections', async () => {
+  // Get initial pool status
+  const initialStatus = pooledClient.getPoolStatus();
+  console.log('📊 Initial status:', initialStatus);
+  
+  // Send emails sequentially to test connection reuse
+  const emailCount = 10;
+  const connectionCounts = [];
+  
+  for (let i = 0; i < emailCount; i++) {
+    const email = new Email({
+      from: 'test@example.com',
+      to: 'recipient@example.com',
+      subject: `Sequential Email ${i}`,
+      text: `Testing connection reuse - email ${i}`
+    });
+    
+    await pooledClient.sendMail(email);
+    
+    const status = pooledClient.getPoolStatus();
+    connectionCounts.push(status.total);
+  }
+  
+  // Check that connections were reused (total shouldn't grow linearly)
+  const maxConnections = Math.max(...connectionCounts);
+  expect(maxConnections).toBeLessThan(emailCount); // Should reuse connections
+  
+  console.log(`✅ Sent ${emailCount} emails using max ${maxConnections} connections`);
+  console.log('📊 Connection counts:', connectionCounts);
+});
+
+tap.test('CCM-04: Connection Pooling - should respect max connections limit', async () => {
+  // Create a client with small pool
+  const limitedClient = createPooledSmtpClient({
+    host: testServer.hostname,
+    port: testServer.port,
+    secure: false,
+    maxConnections: 2, // Very small pool
+    connectionTimeout: 5000
+  });
+  
+  // Send many concurrent emails
+  const emailPromises = [];
+  for (let i = 0; i < 10; i++) {
+    const email = new Email({
+      from: 'test@example.com',
+      to: `test${i}@example.com`,
+      subject: `Pool Limit Test ${i}`,
+      text: 'Testing pool limits'
+    });
+    emailPromises.push(limitedClient.sendMail(email));
+  }
+  
+  // Monitor pool during sending
+  const checkInterval = setInterval(() => {
+    const status = limitedClient.getPoolStatus();
+    console.log('📊 Pool status during load:', status);
+    expect(status.total).toBeLessThanOrEqual(2); // Should never exceed max
+  }, 100);
+  
+  await Promise.all(emailPromises);
+  clearInterval(checkInterval);
+  
+  await limitedClient.close();
+  console.log('✅ Connection pool respected max connections limit');
+});
+
+tap.test('CCM-04: Connection Pooling - should handle connection failures in pool', async () => {
+  // Create a new pooled client
+  const resilientClient = createPooledSmtpClient({
+    host: testServer.hostname,
+    port: testServer.port,
+    secure: false,
+    maxConnections: 3,
+    connectionTimeout: 5000
+  });
+  
+  // Send some emails successfully
+  for (let i = 0; i < 3; i++) {
+    const email = new Email({
+      from: 'test@example.com',
+      to: 'recipient@example.com',
+      subject: `Pre-failure Email ${i}`,
+      text: 'Before simulated failure'
+    });
+    
+    const result = await resilientClient.sendMail(email);
+    expect(result.success).toBeTrue();
+  }
+  
+  // Pool should recover and continue working
+  const poolStatus = resilientClient.getPoolStatus();
+  console.log('📊 Pool status after recovery test:', poolStatus);
+  expect(poolStatus.total).toBeGreaterThanOrEqual(1);
+  
+  await resilientClient.close();
+  console.log('✅ Connection pool handled failures gracefully');
+});
+
+tap.test('CCM-04: Connection Pooling - should clean up idle connections', async () => {
+  // Create client with specific idle settings
+  const idleClient = createPooledSmtpClient({
+    host: testServer.hostname,
+    port: testServer.port,
+    secure: false,
+    maxConnections: 5,
+    connectionTimeout: 5000
+  });
+  
+  // Send burst of emails
+  const promises = [];
+  for (let i = 0; i < 5; i++) {
+    const email = new Email({
+      from: 'test@example.com',
+      to: 'recipient@example.com',
+      subject: `Idle Test ${i}`,
+      text: 'Testing idle cleanup'
+    });
+    promises.push(idleClient.sendMail(email));
+  }
+  
+  await Promise.all(promises);
+  
+  const activeStatus = idleClient.getPoolStatus();
+  console.log('📊 Pool status after burst:', activeStatus);
+  
+  // Wait for connections to become idle
+  await new Promise(resolve => setTimeout(resolve, 2000));
+  
+  const idleStatus = idleClient.getPoolStatus();
+  console.log('📊 Pool status after idle period:', idleStatus);
+  
+  await idleClient.close();
+  console.log('✅ Idle connection management working');
+});
+
+tap.test('cleanup - close pooled client', async () => {
+  if (pooledClient && pooledClient.isConnected()) {
+    await pooledClient.close();
+    
+    // Verify pool is cleaned up
+    const finalStatus = pooledClient.getPoolStatus();
+    console.log('📊 Final pool status:', finalStatus);
+  }
+});
+
+tap.test('cleanup - stop SMTP server', async () => {
+  await stopTestServer(testServer);
+});
+
+tap.start();

test/suite/smtpclient_connection/test.ccm-05.connection-reuse.ts

@@ -0,0 +1,290 @@
+import { tap, expect } from '@git.zone/tstest/tapbundle';
+import { startTestServer, stopTestServer, type ITestServer } from '../../helpers/server.loader.js';
+import { createSmtpClient } from '../../../ts/mail/delivery/smtpclient/index.js';
+import type { SmtpClient } from '../../../ts/mail/delivery/smtpclient/smtp-client.js';
+import { Email } from '../../../ts/mail/core/classes.email.js';
+
+let testServer: ITestServer;
+let smtpClient: SmtpClient;
+
+tap.test('setup - start SMTP server for connection reuse test', async () => {
+  testServer = await startTestServer({
+    port: 2531,
+    tlsEnabled: false,
+    authRequired: false
+  });
+  
+  expect(testServer.port).toEqual(2531);
+});
+
+tap.test('CCM-05: Connection Reuse - should reuse single connection for multiple emails', async () => {
+  const startTime = Date.now();
+  
+  smtpClient = createSmtpClient({
+    host: testServer.hostname,
+    port: testServer.port,
+    secure: false,
+    connectionTimeout: 5000,
+    debug: true
+  });
+  
+  // Verify initial connection
+  await smtpClient.verify();
+  expect(smtpClient.isConnected()).toBeTrue();
+  
+  // Send multiple emails on same connection
+  const emailCount = 5;
+  const results = [];
+  
+  for (let i = 0; i < emailCount; i++) {
+    const email = new Email({
+      from: 'sender@example.com',
+      to: 'recipient@example.com',
+      subject: `Connection Reuse Test ${i + 1}`,
+      text: `This is email ${i + 1} using the same connection`
+    });
+    
+    const result = await smtpClient.sendMail(email);
+    results.push(result);
+    
+    // Connection should remain open
+    expect(smtpClient.isConnected()).toBeTrue();
+  }
+  
+  // All emails should succeed
+  results.forEach((result, index) => {
+    expect(result.success).toBeTrue();
+    console.log(`✅ Email ${index + 1} sent successfully`);
+  });
+  
+  const duration = Date.now() - startTime;
+  console.log(`✅ Sent ${emailCount} emails on single connection in ${duration}ms`);
+});
+
+tap.test('CCM-05: Connection Reuse - should track message count per connection', async () => {
+  // Create a new client with message limit
+  const limitedClient = createSmtpClient({
+    host: testServer.hostname,
+    port: testServer.port,
+    secure: false,
+    maxMessages: 3, // Limit messages per connection
+    connectionTimeout: 5000
+  });
+  
+  // Send emails up to and beyond the limit
+  for (let i = 0; i < 5; i++) {
+    const email = new Email({
+      from: 'sender@example.com',
+      to: 'recipient@example.com',
+      subject: `Message Limit Test ${i + 1}`,
+      text: `Testing message limits`
+    });
+    
+    const result = await limitedClient.sendMail(email);
+    expect(result.success).toBeTrue();
+    
+    // After 3 messages, connection should be refreshed
+    if (i === 2) {
+      console.log('✅ Connection should refresh after message limit');
+    }
+  }
+  
+  await limitedClient.close();
+});
+
+tap.test('CCM-05: Connection Reuse - should handle connection state changes', async () => {
+  // Monitor connection state during reuse
+  let connectionEvents = 0;
+  
+  const eventClient = createSmtpClient({
+    host: testServer.hostname,
+    port: testServer.port,
+    secure: false,
+    connectionTimeout: 5000
+  });
+  
+  eventClient.on('connect', () => connectionEvents++);
+  
+  // First email
+  const email1 = new Email({
+    from: 'sender@example.com',
+    to: 'recipient@example.com',
+    subject: 'First Email',
+    text: 'Testing connection events'
+  });
+  
+  await eventClient.sendMail(email1);
+  const firstConnectCount = connectionEvents;
+  
+  // Second email (should reuse connection)
+  const email2 = new Email({
+    from: 'sender@example.com',
+    to: 'recipient@example.com',
+    subject: 'Second Email',
+    text: 'Should reuse connection'
+  });
+  
+  await eventClient.sendMail(email2);
+  
+  // Should not have created new connection
+  expect(connectionEvents).toEqual(firstConnectCount);
+  
+  await eventClient.close();
+  console.log(`✅ Connection reused (${connectionEvents} total connections)`);
+});
+
+tap.test('CCM-05: Connection Reuse - should handle idle connection timeout', async () => {
+  const idleClient = createSmtpClient({
+    host: testServer.hostname,
+    port: testServer.port,
+    secure: false,
+    connectionTimeout: 5000,
+    socketTimeout: 3000 // Short timeout for testing
+  });
+  
+  // Send first email
+  const email1 = new Email({
+    from: 'sender@example.com',
+    to: 'recipient@example.com',
+    subject: 'Pre-idle Email',
+    text: 'Before idle period'
+  });
+  
+  await idleClient.sendMail(email1);
+  expect(idleClient.isConnected()).toBeTrue();
+  
+  // Wait for potential idle timeout
+  console.log('⏳ Testing idle connection behavior...');
+  await new Promise(resolve => setTimeout(resolve, 4000));
+  
+  // Send another email
+  const email2 = new Email({
+    from: 'sender@example.com',
+    to: 'recipient@example.com',
+    subject: 'Post-idle Email',
+    text: 'After idle period'
+  });
+  
+  // Should handle reconnection if needed
+  const result = await idleClient.sendMail(email2);
+  expect(result.success).toBeTrue();
+  
+  await idleClient.close();
+  console.log('✅ Idle connection handling working correctly');
+});
+
+tap.test('CCM-05: Connection Reuse - should optimize performance with reuse', async () => {
+  // Compare performance with and without connection reuse
+  
+  // Test 1: Multiple connections (no reuse)
+  const noReuseStart = Date.now();
+  for (let i = 0; i < 3; i++) {
+    const tempClient = createSmtpClient({
+      host: testServer.hostname,
+      port: testServer.port,
+      secure: false,
+      connectionTimeout: 5000
+    });
+    
+    const email = new Email({
+      from: 'sender@example.com',
+      to: 'recipient@example.com',
+      subject: `No Reuse ${i}`,
+      text: 'Testing without reuse'
+    });
+    
+    await tempClient.sendMail(email);
+    await tempClient.close();
+  }
+  const noReuseDuration = Date.now() - noReuseStart;
+  
+  // Test 2: Single connection (with reuse)
+  const reuseStart = Date.now();
+  const reuseClient = createSmtpClient({
+    host: testServer.hostname,
+    port: testServer.port,
+    secure: false,
+    connectionTimeout: 5000
+  });
+  
+  for (let i = 0; i < 3; i++) {
+    const email = new Email({
+      from: 'sender@example.com',
+      to: 'recipient@example.com',
+      subject: `With Reuse ${i}`,
+      text: 'Testing with reuse'
+    });
+    
+    await reuseClient.sendMail(email);
+  }
+  
+  await reuseClient.close();
+  const reuseDuration = Date.now() - reuseStart;
+  
+  console.log(`📊 Performance comparison:`);
+  console.log(`   Without reuse: ${noReuseDuration}ms`);
+  console.log(`   With reuse: ${reuseDuration}ms`);
+  console.log(`   Improvement: ${Math.round((1 - reuseDuration/noReuseDuration) * 100)}%`);
+  
+  // Reuse should be faster
+  expect(reuseDuration).toBeLessThan(noReuseDuration);
+});
+
+tap.test('CCM-05: Connection Reuse - should handle errors without breaking reuse', async () => {
+  const resilientClient = createSmtpClient({
+    host: testServer.hostname,
+    port: testServer.port,
+    secure: false,
+    connectionTimeout: 5000
+  });
+  
+  // Send valid email
+  const validEmail = new Email({
+    from: 'sender@example.com',
+    to: 'recipient@example.com',
+    subject: 'Valid Email',
+    text: 'This should work'
+  });
+  
+  const result1 = await resilientClient.sendMail(validEmail);
+  expect(result1.success).toBeTrue();
+  
+  // Try to send invalid email
+  try {
+    const invalidEmail = new Email({
+      from: 'invalid sender format',
+      to: 'recipient@example.com',
+      subject: 'Invalid Email',
+      text: 'This should fail'
+    });
+    await resilientClient.sendMail(invalidEmail);
+  } catch (error) {
+    console.log('✅ Invalid email rejected as expected');
+  }
+  
+  // Connection should still be usable
+  const validEmail2 = new Email({
+    from: 'sender@example.com',
+    to: 'recipient@example.com',
+    subject: 'Valid Email After Error',
+    text: 'Connection should still work'
+  });
+  
+  const result2 = await resilientClient.sendMail(validEmail2);
+  expect(result2.success).toBeTrue();
+  
+  await resilientClient.close();
+  console.log('✅ Connection reuse survived error condition');
+});
+
+tap.test('cleanup - close SMTP client', async () => {
+  if (smtpClient && smtpClient.isConnected()) {
+    await smtpClient.close();
+  }
+});
+
+tap.test('cleanup - stop SMTP server', async () => {
+  await stopTestServer(testServer);
+});
+
+tap.start();

test/suite/smtpclient_connection/test.ccm-06.connection-timeout.ts

@@ -0,0 +1,285 @@
+import { tap, expect } from '@git.zone/tstest/tapbundle';
+import { startTestServer, stopTestServer, type ITestServer } from '../../helpers/server.loader.js';
+import { createSmtpClient } from '../../../ts/mail/delivery/smtpclient/index.js';
+import type { SmtpClient } from '../../../ts/mail/delivery/smtpclient/smtp-client.js';
+import { Email } from '../../../ts/mail/core/classes.email.js';
+import * as net from 'net';
+
+let testServer: ITestServer;
+
+tap.test('setup - start SMTP server for timeout tests', async () => {
+  testServer = await startTestServer({
+    port: 2532,
+    tlsEnabled: false,
+    authRequired: false
+  });
+  
+  expect(testServer.port).toEqual(2532);
+});
+
+tap.test('CCM-06: Connection Timeout - should timeout on unresponsive server', async () => {
+  const startTime = Date.now();
+  let timeoutError = false;
+  
+  try {
+    const timeoutClient = createSmtpClient({
+      host: testServer.hostname,
+      port: 9999, // Non-existent port
+      secure: false,
+      connectionTimeout: 2000, // 2 second timeout
+      debug: true
+    });
+    
+    await timeoutClient.verify();
+  } catch (error: any) {
+    timeoutError = true;
+    const duration = Date.now() - startTime;
+    
+    expect(error).toBeInstanceOf(Error);
+    expect(duration).toBeLessThan(3000); // Should timeout within 3s
+    expect(duration).toBeGreaterThan(1500); // But not too early
+    
+    console.log(`✅ Connection timeout after ${duration}ms`);
+    console.log(`   Error: ${error.message}`);
+  }
+  
+  expect(timeoutError).toBeTrue();
+});
+
+tap.test('CCM-06: Connection Timeout - should handle slow server response', async () => {
+  // Create a mock slow server
+  const slowServer = net.createServer((socket) => {
+    // Accept connection but delay response
+    setTimeout(() => {
+      socket.write('220 Slow server ready\r\n');
+    }, 3000); // 3 second delay
+  });
+  
+  await new Promise<void>((resolve) => {
+    slowServer.listen(2533, () => resolve());
+  });
+  
+  const startTime = Date.now();
+  let timeoutOccurred = false;
+  
+  try {
+    const slowClient = createSmtpClient({
+      host: 'localhost',
+      port: 2533,
+      secure: false,
+      connectionTimeout: 1000, // 1 second timeout
+      debug: true
+    });
+    
+    await slowClient.verify();
+  } catch (error: any) {
+    timeoutOccurred = true;
+    const duration = Date.now() - startTime;
+    
+    expect(duration).toBeLessThan(2000);
+    console.log(`✅ Slow server timeout after ${duration}ms`);
+  }
+  
+  expect(timeoutOccurred).toBeTrue();
+  
+  slowServer.close();
+  await new Promise(resolve => setTimeout(resolve, 100));
+});
+
+tap.test('CCM-06: Connection Timeout - should respect socket timeout during data transfer', async () => {
+  const socketTimeoutClient = createSmtpClient({
+    host: testServer.hostname,
+    port: testServer.port,
+    secure: false,
+    connectionTimeout: 5000,
+    socketTimeout: 10000, // 10 second socket timeout
+    debug: true
+  });
+  
+  await socketTimeoutClient.verify();
+  
+  // Send a normal email
+  const email = new Email({
+    from: 'sender@example.com',
+    to: 'recipient@example.com',
+    subject: 'Socket Timeout Test',
+    text: 'Testing socket timeout configuration'
+  });
+  
+  const result = await socketTimeoutClient.sendMail(email);
+  expect(result.success).toBeTrue();
+  
+  await socketTimeoutClient.close();
+  console.log('✅ Socket timeout configuration applied');
+});
+
+tap.test('CCM-06: Connection Timeout - should handle timeout during TLS handshake', async () => {
+  // Create a server that accepts connections but doesn't complete TLS
+  const badTlsServer = net.createServer((socket) => {
+    // Accept connection but don't respond to TLS
+    socket.on('data', () => {
+      // Do nothing - simulate hung TLS handshake
+    });
+  });
+  
+  await new Promise<void>((resolve) => {
+    badTlsServer.listen(2534, () => resolve());
+  });
+  
+  let tlsTimeoutError = false;
+  const startTime = Date.now();
+  
+  try {
+    const tlsTimeoutClient = createSmtpClient({
+      host: 'localhost',
+      port: 2534,
+      secure: true, // Try TLS
+      connectionTimeout: 2000,
+      tls: {
+        rejectUnauthorized: false
+      }
+    });
+    
+    await tlsTimeoutClient.verify();
+  } catch (error: any) {
+    tlsTimeoutError = true;
+    const duration = Date.now() - startTime;
+    
+    expect(duration).toBeLessThan(3000);
+    console.log(`✅ TLS handshake timeout after ${duration}ms`);
+  }
+  
+  expect(tlsTimeoutError).toBeTrue();
+  
+  badTlsServer.close();
+  await new Promise(resolve => setTimeout(resolve, 100));
+});
+
+tap.test('CCM-06: Connection Timeout - should not timeout on successful quick connection', async () => {
+  const quickClient = createSmtpClient({
+    host: testServer.hostname,
+    port: testServer.port,
+    secure: false,
+    connectionTimeout: 30000, // Very long timeout
+    debug: true
+  });
+  
+  const startTime = Date.now();
+  
+  const isConnected = await quickClient.verify();
+  const duration = Date.now() - startTime;
+  
+  expect(isConnected).toBeTrue();
+  expect(duration).toBeLessThan(5000); // Should connect quickly
+  
+  await quickClient.close();
+  console.log(`✅ Quick connection established in ${duration}ms`);
+});
+
+tap.test('CCM-06: Connection Timeout - should handle timeout during authentication', async () => {
+  // Start auth server
+  const authServer = await startTestServer({
+    port: 2535,
+    authRequired: true
+  });
+  
+  // Create mock auth that delays
+  const authTimeoutClient = createSmtpClient({
+    host: authServer.hostname,
+    port: authServer.port,
+    secure: false,
+    connectionTimeout: 5000,
+    socketTimeout: 1000, // Very short socket timeout
+    auth: {
+      user: 'testuser',
+      pass: 'testpass'
+    }
+  });
+  
+  try {
+    await authTimeoutClient.verify();
+    // If this succeeds, auth was fast enough
+    await authTimeoutClient.close();
+    console.log('✅ Authentication completed within timeout');
+  } catch (error) {
+    console.log('✅ Authentication timeout handled');
+  }
+  
+  await stopTestServer(authServer);
+});
+
+tap.test('CCM-06: Connection Timeout - should apply different timeouts for different operations', async () => {
+  const multiTimeoutClient = createSmtpClient({
+    host: testServer.hostname,
+    port: testServer.port,
+    secure: false,
+    connectionTimeout: 5000,  // Connection establishment
+    socketTimeout: 30000,     // Data operations
+    debug: true
+  });
+  
+  // Connection should be quick
+  const connectStart = Date.now();
+  await multiTimeoutClient.verify();
+  const connectDuration = Date.now() - connectStart;
+  
+  expect(connectDuration).toBeLessThan(5000);
+  
+  // Send email with potentially longer operation
+  const email = new Email({
+    from: 'sender@example.com',
+    to: 'recipient@example.com',
+    subject: 'Multi-timeout Test',
+    text: 'Testing different timeout values',
+    attachments: [{
+      filename: 'test.txt',
+      content: Buffer.from('Test content'),
+      contentType: 'text/plain'
+    }]
+  });
+  
+  const sendStart = Date.now();
+  const result = await multiTimeoutClient.sendMail(email);
+  const sendDuration = Date.now() - sendStart;
+  
+  expect(result.success).toBeTrue();
+  console.log(`✅ Different timeouts applied: connect=${connectDuration}ms, send=${sendDuration}ms`);
+  
+  await multiTimeoutClient.close();
+});
+
+tap.test('CCM-06: Connection Timeout - should retry after timeout with pooled connections', async () => {
+  const retryClient = createSmtpClient({
+    host: testServer.hostname,
+    port: testServer.port,
+    secure: false,
+    pool: true,
+    maxConnections: 2,
+    connectionTimeout: 5000,
+    debug: true
+  });
+  
+  // First connection should succeed
+  const email1 = new Email({
+    from: 'sender@example.com',
+    to: 'recipient@example.com',
+    subject: 'Pre-timeout Email',
+    text: 'Before any timeout'
+  });
+  
+  const result1 = await retryClient.sendMail(email1);
+  expect(result1.success).toBeTrue();
+  
+  // Pool should handle connection management
+  const poolStatus = retryClient.getPoolStatus();
+  console.log('📊 Pool status:', poolStatus);
+  
+  await retryClient.close();
+  console.log('✅ Connection pool handles timeouts gracefully');
+});
+
+tap.test('cleanup - stop SMTP server', async () => {
+  await stopTestServer(testServer);
+});
+
+tap.start();

test/suite/smtpclient_connection/test.ccm-07.automatic-reconnection.ts

@@ -0,0 +1,308 @@
+import { tap, expect } from '@git.zone/tstest/tapbundle';
+import { startTestServer, stopTestServer, type ITestServer } from '../../helpers/server.loader.js';
+import { createSmtpClient, createPooledSmtpClient } from '../../../ts/mail/delivery/smtpclient/index.js';
+import type { SmtpClient } from '../../../ts/mail/delivery/smtpclient/smtp-client.js';
+import { Email } from '../../../ts/mail/core/classes.email.js';
+import * as net from 'net';
+
+let testServer: ITestServer;
+
+tap.test('setup - start SMTP server for reconnection tests', async () => {
+  testServer = await startTestServer({
+    port: 2533,
+    tlsEnabled: false,
+    authRequired: false
+  });
+  
+  expect(testServer.port).toEqual(2533);
+});
+
+tap.test('CCM-07: Automatic Reconnection - should reconnect after connection loss', async () => {
+  const client = createSmtpClient({
+    host: testServer.hostname,
+    port: testServer.port,
+    secure: false,
+    connectionTimeout: 5000,
+    debug: true
+  });
+  
+  // First connection and email
+  const email1 = new Email({
+    from: 'sender@example.com',
+    to: 'recipient@example.com',
+    subject: 'Before Disconnect',
+    text: 'First email before connection loss'
+  });
+  
+  const result1 = await client.sendMail(email1);
+  expect(result1.success).toBeTrue();
+  expect(client.isConnected()).toBeTrue();
+  
+  // Force disconnect
+  await client.close();
+  expect(client.isConnected()).toBeFalse();
+  
+  // Try to send another email - should auto-reconnect
+  const email2 = new Email({
+    from: 'sender@example.com',
+    to: 'recipient@example.com',
+    subject: 'After Reconnect',
+    text: 'Email after automatic reconnection'
+  });
+  
+  const result2 = await client.sendMail(email2);
+  expect(result2.success).toBeTrue();
+  expect(client.isConnected()).toBeTrue();
+  
+  await client.close();
+  console.log('✅ Automatic reconnection successful');
+});
+
+tap.test('CCM-07: Automatic Reconnection - pooled client should reconnect failed connections', async () => {
+  const pooledClient = createPooledSmtpClient({
+    host: testServer.hostname,
+    port: testServer.port,
+    secure: false,
+    maxConnections: 3,
+    connectionTimeout: 5000,
+    debug: true
+  });
+  
+  // Send emails to establish pool connections
+  const promises = [];
+  for (let i = 0; i < 3; i++) {
+    const email = new Email({
+      from: 'sender@example.com',
+      to: `recipient${i}@example.com`,
+      subject: `Pool Test ${i}`,
+      text: 'Testing connection pool'
+    });
+    promises.push(pooledClient.sendMail(email));
+  }
+  
+  await Promise.all(promises);
+  
+  const poolStatus1 = pooledClient.getPoolStatus();
+  console.log('📊 Pool status before disruption:', poolStatus1);
+  
+  // Send more emails - pool should handle any connection issues
+  const promises2 = [];
+  for (let i = 0; i < 5; i++) {
+    const email = new Email({
+      from: 'sender@example.com',
+      to: `recipient${i}@example.com`,
+      subject: `Pool Recovery ${i}`,
+      text: 'Testing pool recovery'
+    });
+    promises2.push(pooledClient.sendMail(email));
+  }
+  
+  const results = await Promise.all(promises2);
+  results.forEach(result => {
+    expect(result.success).toBeTrue();
+  });
+  
+  const poolStatus2 = pooledClient.getPoolStatus();
+  console.log('📊 Pool status after recovery:', poolStatus2);
+  
+  await pooledClient.close();
+  console.log('✅ Connection pool handles reconnection automatically');
+});
+
+tap.test('CCM-07: Automatic Reconnection - should handle server restart', async () => {
+  // Create client
+  const client = createSmtpClient({
+    host: testServer.hostname,
+    port: testServer.port,
+    secure: false,
+    connectionTimeout: 5000
+  });
+  
+  // Send first email
+  const email1 = new Email({
+    from: 'sender@example.com',
+    to: 'recipient@example.com',
+    subject: 'Before Server Restart',
+    text: 'Email before server restart'
+  });
+  
+  const result1 = await client.sendMail(email1);
+  expect(result1.success).toBeTrue();
+  
+  // Simulate server restart
+  console.log('🔄 Simulating server restart...');
+  await stopTestServer(testServer);
+  await new Promise(resolve => setTimeout(resolve, 1000));
+  
+  // Restart server on same port
+  testServer = await startTestServer({
+    port: 2533,
+    tlsEnabled: false,
+    authRequired: false
+  });
+  
+  // Try to send another email
+  const email2 = new Email({
+    from: 'sender@example.com',
+    to: 'recipient@example.com',
+    subject: 'After Server Restart',
+    text: 'Email after server restart'
+  });
+  
+  const result2 = await client.sendMail(email2);
+  expect(result2.success).toBeTrue();
+  
+  await client.close();
+  console.log('✅ Client recovered from server restart');
+});
+
+tap.test('CCM-07: Automatic Reconnection - should handle network interruption', async () => {
+  const client = createSmtpClient({
+    host: testServer.hostname,
+    port: testServer.port,
+    secure: false,
+    connectionTimeout: 5000,
+    socketTimeout: 10000
+  });
+  
+  // Establish connection
+  await client.verify();
+  
+  // Send emails with simulated network issues
+  for (let i = 0; i < 3; i++) {
+    const email = new Email({
+      from: 'sender@example.com',
+      to: 'recipient@example.com',
+      subject: `Network Test ${i}`,
+      text: `Testing network resilience ${i}`
+    });
+    
+    try {
+      const result = await client.sendMail(email);
+      expect(result.success).toBeTrue();
+      console.log(`✅ Email ${i + 1} sent successfully`);
+    } catch (error) {
+      console.log(`⚠️ Email ${i + 1} failed, will retry`);
+      // Client should recover on next attempt
+    }
+    
+    // Add small delay between sends
+    await new Promise(resolve => setTimeout(resolve, 100));
+  }
+  
+  await client.close();
+});
+
+tap.test('CCM-07: Automatic Reconnection - should limit reconnection attempts', async () => {
+  // Connect to a port that will be closed
+  const tempServer = net.createServer();
+  await new Promise<void>((resolve) => {
+    tempServer.listen(2534, () => resolve());
+  });
+  
+  const client = createSmtpClient({
+    host: 'localhost',
+    port: 2534,
+    secure: false,
+    connectionTimeout: 2000
+  });
+  
+  // Close the server to simulate failure
+  tempServer.close();
+  await new Promise(resolve => setTimeout(resolve, 100));
+  
+  let errorCount = 0;
+  const maxAttempts = 3;
+  
+  // Try multiple times
+  for (let i = 0; i < maxAttempts; i++) {
+    try {
+      await client.verify();
+    } catch (error) {
+      errorCount++;
+    }
+  }
+  
+  expect(errorCount).toEqual(maxAttempts);
+  console.log('✅ Reconnection attempts are limited to prevent infinite loops');
+});
+
+tap.test('CCM-07: Automatic Reconnection - should maintain state after reconnect', async () => {
+  const client = createSmtpClient({
+    host: testServer.hostname,
+    port: testServer.port,
+    secure: false,
+    connectionTimeout: 5000
+  });
+  
+  // Send email with specific settings
+  const email1 = new Email({
+    from: 'sender@example.com',
+    to: 'recipient@example.com',
+    subject: 'State Test 1',
+    text: 'Testing state persistence',
+    priority: 'high',
+    headers: {
+      'X-Test-ID': 'test-123'
+    }
+  });
+  
+  const result1 = await client.sendMail(email1);
+  expect(result1.success).toBeTrue();
+  
+  // Force reconnection
+  await client.close();
+  
+  // Send another email - client state should be maintained
+  const email2 = new Email({
+    from: 'sender@example.com',
+    to: 'recipient@example.com',
+    subject: 'State Test 2',
+    text: 'After reconnection',
+    priority: 'high',
+    headers: {
+      'X-Test-ID': 'test-456'
+    }
+  });
+  
+  const result2 = await client.sendMail(email2);
+  expect(result2.success).toBeTrue();
+  
+  await client.close();
+  console.log('✅ Client state maintained after reconnection');
+});
+
+tap.test('CCM-07: Automatic Reconnection - should handle rapid reconnections', async () => {
+  const client = createSmtpClient({
+    host: testServer.hostname,
+    port: testServer.port,
+    secure: false,
+    connectionTimeout: 5000
+  });
+  
+  // Rapid connect/disconnect cycles
+  for (let i = 0; i < 5; i++) {
+    const email = new Email({
+      from: 'sender@example.com',
+      to: 'recipient@example.com',
+      subject: `Rapid Test ${i}`,
+      text: 'Testing rapid reconnections'
+    });
+    
+    const result = await client.sendMail(email);
+    expect(result.success).toBeTrue();
+    
+    // Force disconnect
+    await client.close();
+    
+    // No delay - immediate next attempt
+  }
+  
+  console.log('✅ Rapid reconnections handled successfully');
+});
+
+tap.test('cleanup - stop SMTP server', async () => {
+  await stopTestServer(testServer);
+});
+
+tap.start();

test/suite/smtpclient_connection/test.ccm-08.dns-resolution.ts

@@ -0,0 +1,135 @@
+import { tap, expect } from '@git.zone/tstest/tapbundle';
+import { startTestSmtpServer } from '../../helpers/server.loader.js';
+import * as dns from 'dns';
+import { promisify } from 'util';
+
+const resolveMx = promisify(dns.resolveMx);
+const resolve4 = promisify(dns.resolve4);
+const resolve6 = promisify(dns.resolve6);
+
+let testServer: any;
+
+tap.test('setup test SMTP server', async () => {
+  testServer = await startTestSmtpServer();
+  expect(testServer).toBeTruthy();
+  expect(testServer.port).toBeGreaterThan(0);
+});
+
+tap.test('CCM-08: DNS resolution and MX record lookup', async () => {
+  // Test basic DNS resolution
+  try {
+    const ipv4Addresses = await resolve4('example.com');
+    expect(ipv4Addresses).toBeArray();
+    expect(ipv4Addresses.length).toBeGreaterThan(0);
+    console.log('IPv4 addresses for example.com:', ipv4Addresses);
+  } catch (error) {
+    console.log('IPv4 resolution failed (may be expected in test environment):', error.message);
+  }
+
+  // Test IPv6 resolution
+  try {
+    const ipv6Addresses = await resolve6('example.com');
+    expect(ipv6Addresses).toBeArray();
+    console.log('IPv6 addresses for example.com:', ipv6Addresses);
+  } catch (error) {
+    console.log('IPv6 resolution failed (common for many domains):', error.message);
+  }
+
+  // Test MX record lookup
+  try {
+    const mxRecords = await resolveMx('example.com');
+    expect(mxRecords).toBeArray();
+    if (mxRecords.length > 0) {
+      expect(mxRecords[0]).toHaveProperty('priority');
+      expect(mxRecords[0]).toHaveProperty('exchange');
+      console.log('MX records for example.com:', mxRecords);
+    }
+  } catch (error) {
+    console.log('MX record lookup failed (may be expected in test environment):', error.message);
+  }
+
+  // Test local resolution (should work in test environment)
+  try {
+    const localhostIpv4 = await resolve4('localhost');
+    expect(localhostIpv4).toContain('127.0.0.1');
+  } catch (error) {
+    // Fallback for environments where localhost doesn't resolve via DNS
+    console.log('Localhost DNS resolution not available, using direct IP');
+  }
+
+  // Test invalid domain handling
+  try {
+    await resolve4('this-domain-definitely-does-not-exist-12345.com');
+    expect(true).toBeFalsy(); // Should not reach here
+  } catch (error) {
+    expect(error.code).toMatch(/ENOTFOUND|ENODATA/);
+  }
+
+  // Test MX record priority sorting
+  const mockMxRecords = [
+    { priority: 20, exchange: 'mx2.example.com' },
+    { priority: 10, exchange: 'mx1.example.com' },
+    { priority: 30, exchange: 'mx3.example.com' }
+  ];
+  
+  const sortedRecords = mockMxRecords.sort((a, b) => a.priority - b.priority);
+  expect(sortedRecords[0].exchange).toEqual('mx1.example.com');
+  expect(sortedRecords[1].exchange).toEqual('mx2.example.com');
+  expect(sortedRecords[2].exchange).toEqual('mx3.example.com');
+});
+
+tap.test('CCM-08: DNS caching behavior', async () => {
+  const startTime = Date.now();
+  
+  // First resolution (cold cache)
+  try {
+    await resolve4('example.com');
+  } catch (error) {
+    // Ignore errors, we're testing timing
+  }
+  
+  const firstResolutionTime = Date.now() - startTime;
+  
+  // Second resolution (potentially cached)
+  const secondStartTime = Date.now();
+  try {
+    await resolve4('example.com');
+  } catch (error) {
+    // Ignore errors, we're testing timing
+  }
+  
+  const secondResolutionTime = Date.now() - secondStartTime;
+  
+  console.log(`First resolution: ${firstResolutionTime}ms, Second resolution: ${secondResolutionTime}ms`);
+  
+  // Note: We can't guarantee caching behavior in all environments
+  // so we just log the times for manual inspection
+});
+
+tap.test('CCM-08: Multiple A record handling', async () => {
+  // Test handling of domains with multiple A records
+  try {
+    const googleIps = await resolve4('google.com');
+    if (googleIps.length > 1) {
+      expect(googleIps).toBeArray();
+      expect(googleIps.length).toBeGreaterThan(1);
+      console.log('Multiple A records found for google.com:', googleIps);
+      
+      // Verify all are valid IPv4 addresses
+      const ipv4Regex = /^(\d{1,3}\.){3}\d{1,3}$/;
+      for (const ip of googleIps) {
+        expect(ip).toMatch(ipv4Regex);
+      }
+    }
+  } catch (error) {
+    console.log('Could not resolve google.com:', error.message);
+  }
+});
+
+tap.test('cleanup test SMTP server', async () => {
+  if (testServer) {
+    await testServer.stop();
+  }
+});
+
+export default tap.start();

test/suite/smtpclient_connection/test.ccm-09.ipv6-dual-stack.ts

@@ -0,0 +1,201 @@
+import { tap, expect } from '@git.zone/tstest/tapbundle';
+import { startTestSmtpServer } from '../../helpers/server.loader.js';
+import { createSmtpClient } from '../../helpers/smtp.client.js';
+import * as net from 'net';
+import * as os from 'os';
+
+let testServer: any;
+
+tap.test('setup test SMTP server', async () => {
+  testServer = await startTestSmtpServer();
+  expect(testServer).toBeTruthy();
+  expect(testServer.port).toBeGreaterThan(0);
+});
+
+tap.test('CCM-09: Check system IPv6 support', async () => {
+  const networkInterfaces = os.networkInterfaces();
+  let hasIPv6 = false;
+  
+  for (const interfaceName in networkInterfaces) {
+    const interfaces = networkInterfaces[interfaceName];
+    if (interfaces) {
+      for (const iface of interfaces) {
+        if (iface.family === 'IPv6' && !iface.internal) {
+          hasIPv6 = true;
+          console.log(`Found IPv6 address: ${iface.address} on ${interfaceName}`);
+        }
+      }
+    }
+  }
+  
+  console.log(`System has IPv6 support: ${hasIPv6}`);
+});
+
+tap.test('CCM-09: IPv4 connection test', async () => {
+  const smtpClient = createSmtpClient({
+    host: '127.0.0.1', // Explicit IPv4
+    port: testServer.port,
+    secure: false,
+    connectionTimeout: 5000,
+    debug: true
+  });
+
+  let connected = false;
+  let connectionFamily = '';
+
+  smtpClient.on('connection', (info: any) => {
+    connected = true;
+    if (info && info.socket) {
+      connectionFamily = info.socket.remoteFamily || '';
+    }
+  });
+
+  smtpClient.on('error', (error: Error) => {
+    console.error('IPv4 connection error:', error.message);
+  });
+
+  // Test connection
+  const result = await smtpClient.connect();
+  expect(result).toBeTruthy();
+  expect(smtpClient.isConnected()).toBeTruthy();
+  
+  console.log(`Connected via IPv4, family: ${connectionFamily}`);
+  
+  await smtpClient.close();
+});
+
+tap.test('CCM-09: IPv6 connection test (if supported)', async () => {
+  // Check if IPv6 is available
+  const hasIPv6 = await new Promise<boolean>((resolve) => {
+    const testSocket = net.createConnection({
+      host: '::1',
+      port: 1, // Any port, will fail but tells us if IPv6 works
+      timeout: 100
+    });
+    
+    testSocket.on('error', (err: any) => {
+      // ECONNREFUSED means IPv6 works but port is closed (expected)
+      // ENETUNREACH or EAFNOSUPPORT means IPv6 not available
+      resolve(err.code === 'ECONNREFUSED');
+    });
+    
+    testSocket.on('connect', () => {
+      testSocket.end();
+      resolve(true);
+    });
+  });
+
+  if (!hasIPv6) {
+    console.log('IPv6 not available on this system, skipping IPv6 tests');
+    return;
+  }
+
+  // Try IPv6 connection
+  const smtpClient = createSmtpClient({
+    host: '::1', // IPv6 loopback
+    port: testServer.port,
+    secure: false,
+    connectionTimeout: 5000,
+    debug: true
+  });
+
+  let connected = false;
+  let connectionFamily = '';
+
+  smtpClient.on('connection', (info: any) => {
+    connected = true;
+    if (info && info.socket) {
+      connectionFamily = info.socket.remoteFamily || '';
+    }
+  });
+
+  smtpClient.on('error', (error: Error) => {
+    console.error('IPv6 connection error:', error.message);
+  });
+
+  try {
+    const result = await smtpClient.connect();
+    if (result && smtpClient.isConnected()) {
+      console.log(`Connected via IPv6, family: ${connectionFamily}`);
+      await smtpClient.close();
+    }
+  } catch (error) {
+    console.log('IPv6 connection failed (server may not support IPv6):', error.message);
+  }
+});
+
+tap.test('CCM-09: Hostname resolution preference', async () => {
+  // Test that client can handle hostnames that resolve to both IPv4 and IPv6
+  const smtpClient = createSmtpClient({
+    host: 'localhost', // Should resolve to both 127.0.0.1 and ::1
+    port: testServer.port,
+    secure: false,
+    connectionTimeout: 5000,
+    debug: true
+  });
+
+  let connectionInfo: any = null;
+
+  smtpClient.on('connection', (info: any) => {
+    connectionInfo = info;
+  });
+
+  const result = await smtpClient.connect();
+  expect(result).toBeTruthy();
+  expect(smtpClient.isConnected()).toBeTruthy();
+
+  if (connectionInfo && connectionInfo.socket) {
+    console.log(`Connected to localhost via ${connectionInfo.socket.remoteFamily || 'unknown'}`);
+    console.log(`Local address: ${connectionInfo.socket.localAddress}`);
+    console.log(`Remote address: ${connectionInfo.socket.remoteAddress}`);
+  }
+
+  await smtpClient.close();
+});
+
+tap.test('CCM-09: Happy Eyeballs algorithm simulation', async () => {
+  // Test connecting to multiple addresses with preference
+  const addresses = ['127.0.0.1', '::1', 'localhost'];
+  const results: Array<{ address: string; time: number; success: boolean }> = [];
+
+  for (const address of addresses) {
+    const startTime = Date.now();
+    const smtpClient = createSmtpClient({
+      host: address,
+      port: testServer.port,
+      secure: false,
+      connectionTimeout: 1000,
+      debug: false
+    });
+
+    try {
+      const connected = await smtpClient.connect();
+      const elapsed = Date.now() - startTime;
+      results.push({ address, time: elapsed, success: !!connected });
+      
+      if (connected) {
+        await smtpClient.close();
+      }
+    } catch (error) {
+      const elapsed = Date.now() - startTime;
+      results.push({ address, time: elapsed, success: false });
+    }
+  }
+
+  console.log('Connection race results:');
+  results.forEach(r => {
+    console.log(`  ${r.address}: ${r.success ? 'SUCCESS' : 'FAILED'} in ${r.time}ms`);
+  });
+
+  // At least one should succeed
+  const successfulConnections = results.filter(r => r.success);
+  expect(successfulConnections.length).toBeGreaterThan(0);
+});
+
+tap.test('cleanup test SMTP server', async () => {
+  if (testServer) {
+    await testServer.stop();
+  }
+});
+
+export default tap.start();

test/suite/smtpclient_connection/test.ccm-10.proxy-support.ts

@@ -0,0 +1,298 @@
+import { tap, expect } from '@git.zone/tstest/tapbundle';
+import { startTestSmtpServer } from '../../helpers/server.loader.js';
+import { createSmtpClient } from '../../helpers/smtp.client.js';
+import * as net from 'net';
+import * as http from 'http';
+
+let testServer: any;
+let proxyServer: http.Server;
+let socksProxyServer: net.Server;
+
+tap.test('setup test SMTP server', async () => {
+  testServer = await startTestSmtpServer();
+  expect(testServer).toBeTruthy();
+  expect(testServer.port).toBeGreaterThan(0);
+});
+
+tap.test('CCM-10: Setup HTTP CONNECT proxy', async () => {
+  // Create a simple HTTP CONNECT proxy
+  proxyServer = http.createServer();
+  
+  proxyServer.on('connect', (req, clientSocket, head) => {
+    console.log(`Proxy CONNECT request to ${req.url}`);
+    
+    const [host, port] = req.url!.split(':');
+    const serverSocket = net.connect(parseInt(port), host, () => {
+      clientSocket.write('HTTP/1.1 200 Connection Established\r\n' +
+                        'Proxy-agent: Test-Proxy\r\n' +
+                        '\r\n');
+      
+      // Pipe data between client and server
+      serverSocket.pipe(clientSocket);
+      clientSocket.pipe(serverSocket);
+    });
+    
+    serverSocket.on('error', (err) => {
+      console.error('Proxy server socket error:', err);
+      clientSocket.end();
+    });
+    
+    clientSocket.on('error', (err) => {
+      console.error('Proxy client socket error:', err);
+      serverSocket.end();
+    });
+  });
+  
+  await new Promise<void>((resolve) => {
+    proxyServer.listen(0, '127.0.0.1', () => {
+      const address = proxyServer.address() as net.AddressInfo;
+      console.log(`HTTP proxy listening on port ${address.port}`);
+      resolve();
+    });
+  });
+});
+
+tap.test('CCM-10: Test connection through HTTP proxy', async () => {
+  const proxyAddress = proxyServer.address() as net.AddressInfo;
+  
+  // Note: Real SMTP clients would need proxy configuration
+  // This simulates what a proxy-aware SMTP client would do
+  const proxyOptions = {
+    host: proxyAddress.address,
+    port: proxyAddress.port,
+    method: 'CONNECT',
+    path: `127.0.0.1:${testServer.port}`,
+    headers: {
+      'Proxy-Authorization': 'Basic dGVzdDp0ZXN0' // test:test in base64
+    }
+  };
+  
+  const connected = await new Promise<boolean>((resolve) => {
+    const req = http.request(proxyOptions);
+    
+    req.on('connect', (res, socket, head) => {
+      console.log('Connected through proxy, status:', res.statusCode);
+      expect(res.statusCode).toEqual(200);
+      
+      // Now we have a raw socket to the SMTP server through the proxy
+      socket.on('data', (data) => {
+        const response = data.toString();
+        console.log('SMTP response through proxy:', response.trim());
+        if (response.includes('220')) {
+          socket.write('QUIT\r\n');
+          socket.end();
+          resolve(true);
+        }
+      });
+      
+      socket.on('error', (err) => {
+        console.error('Socket error:', err);
+        resolve(false);
+      });
+    });
+    
+    req.on('error', (err) => {
+      console.error('Proxy request error:', err);
+      resolve(false);
+    });
+    
+    req.end();
+  });
+  
+  expect(connected).toBeTruthy();
+});
+
+tap.test('CCM-10: Test SOCKS5 proxy simulation', async () => {
+  // Create a minimal SOCKS5 proxy for testing
+  socksProxyServer = net.createServer((clientSocket) => {
+    let authenticated = false;
+    let targetHost: string;
+    let targetPort: number;
+    
+    clientSocket.on('data', (data) => {
+      if (!authenticated) {
+        // SOCKS5 handshake
+        if (data[0] === 0x05) { // SOCKS version 5
+          // Send back: no authentication required
+          clientSocket.write(Buffer.from([0x05, 0x00]));
+          authenticated = true;
+        }
+      } else if (!targetHost) {
+        // Connection request
+        if (data[0] === 0x05 && data[1] === 0x01) { // CONNECT command
+          const addressType = data[3];
+          
+          if (addressType === 0x01) { // IPv4
+            targetHost = `${data[4]}.${data[5]}.${data[6]}.${data[7]}`;
+            targetPort = (data[8] << 8) + data[9];
+            
+            // Connect to target
+            const serverSocket = net.connect(targetPort, targetHost, () => {
+              // Send success response
+              const response = Buffer.alloc(10);
+              response[0] = 0x05; // SOCKS version
+              response[1] = 0x00; // Success
+              response[2] = 0x00; // Reserved
+              response[3] = 0x01; // IPv4
+              response[4] = data[4]; // Copy address
+              response[5] = data[5];
+              response[6] = data[6];
+              response[7] = data[7];
+              response[8] = data[8]; // Copy port
+              response[9] = data[9];
+              
+              clientSocket.write(response);
+              
+              // Start proxying
+              serverSocket.pipe(clientSocket);
+              clientSocket.pipe(serverSocket);
+            });
+            
+            serverSocket.on('error', (err) => {
+              console.error('SOCKS target connection error:', err);
+              clientSocket.end();
+            });
+          }
+        }
+      }
+    });
+    
+    clientSocket.on('error', (err) => {
+      console.error('SOCKS client error:', err);
+    });
+  });
+  
+  await new Promise<void>((resolve) => {
+    socksProxyServer.listen(0, '127.0.0.1', () => {
+      const address = socksProxyServer.address() as net.AddressInfo;
+      console.log(`SOCKS5 proxy listening on port ${address.port}`);
+      resolve();
+    });
+  });
+  
+  // Test connection through SOCKS proxy
+  const socksAddress = socksProxyServer.address() as net.AddressInfo;
+  const socksClient = net.connect(socksAddress.port, socksAddress.address);
+  
+  const connected = await new Promise<boolean>((resolve) => {
+    let phase = 'handshake';
+    
+    socksClient.on('connect', () => {
+      // Send SOCKS5 handshake
+      socksClient.write(Buffer.from([0x05, 0x01, 0x00])); // Version 5, 1 method, no auth
+    });
+    
+    socksClient.on('data', (data) => {
+      if (phase === 'handshake' && data[0] === 0x05 && data[1] === 0x00) {
+        phase = 'connect';
+        // Send connection request
+        const connectReq = Buffer.alloc(10);
+        connectReq[0] = 0x05; // SOCKS version
+        connectReq[1] = 0x01; // CONNECT
+        connectReq[2] = 0x00; // Reserved
+        connectReq[3] = 0x01; // IPv4
+        connectReq[4] = 127;  // 127.0.0.1
+        connectReq[5] = 0;
+        connectReq[6] = 0;
+        connectReq[7] = 1;
+        connectReq[8] = (testServer.port >> 8) & 0xFF; // Port high byte
+        connectReq[9] = testServer.port & 0xFF; // Port low byte
+        
+        socksClient.write(connectReq);
+      } else if (phase === 'connect' && data[0] === 0x05 && data[1] === 0x00) {
+        phase = 'connected';
+        console.log('Connected through SOCKS5 proxy');
+        // Now we're connected to the SMTP server
+      } else if (phase === 'connected') {
+        const response = data.toString();
+        console.log('SMTP response through SOCKS:', response.trim());
+        if (response.includes('220')) {
+          socksClient.write('QUIT\r\n');
+          socksClient.end();
+          resolve(true);
+        }
+      }
+    });
+    
+    socksClient.on('error', (err) => {
+      console.error('SOCKS client error:', err);
+      resolve(false);
+    });
+    
+    setTimeout(() => resolve(false), 5000); // Timeout after 5 seconds
+  });
+  
+  expect(connected).toBeTruthy();
+});
+
+tap.test('CCM-10: Test proxy authentication failure', async () => {
+  // Create a proxy that requires authentication
+  const authProxyServer = http.createServer();
+  
+  authProxyServer.on('connect', (req, clientSocket, head) => {
+    const authHeader = req.headers['proxy-authorization'];
+    
+    if (!authHeader || authHeader !== 'Basic dGVzdDp0ZXN0') {
+      clientSocket.write('HTTP/1.1 407 Proxy Authentication Required\r\n' +
+                        'Proxy-Authenticate: Basic realm="Test Proxy"\r\n' +
+                        '\r\n');
+      clientSocket.end();
+      return;
+    }
+    
+    // Authentication successful, proceed with connection
+    const [host, port] = req.url!.split(':');
+    const serverSocket = net.connect(parseInt(port), host, () => {
+      clientSocket.write('HTTP/1.1 200 Connection Established\r\n\r\n');
+      serverSocket.pipe(clientSocket);
+      clientSocket.pipe(serverSocket);
+    });
+  });
+  
+  await new Promise<void>((resolve) => {
+    authProxyServer.listen(0, '127.0.0.1', () => {
+      resolve();
+    });
+  });
+  
+  const authProxyAddress = authProxyServer.address() as net.AddressInfo;
+  
+  // Test without authentication
+  const failedAuth = await new Promise<boolean>((resolve) => {
+    const req = http.request({
+      host: authProxyAddress.address,
+      port: authProxyAddress.port,
+      method: 'CONNECT',
+      path: `127.0.0.1:${testServer.port}`
+    });
+    
+    req.on('connect', () => resolve(false));
+    req.on('response', (res) => {
+      expect(res.statusCode).toEqual(407);
+      resolve(true);
+    });
+    req.on('error', () => resolve(false));
+    
+    req.end();
+  });
+  
+  expect(failedAuth).toBeTruthy();
+  
+  authProxyServer.close();
+});
+
+tap.test('cleanup test servers', async () => {
+  if (proxyServer) {
+    await new Promise<void>((resolve) => proxyServer.close(() => resolve()));
+  }
+  
+  if (socksProxyServer) {
+    await new Promise<void>((resolve) => socksProxyServer.close(() => resolve()));
+  }
+  
+  if (testServer) {
+    await testServer.stop();
+  }
+});
+
+export default tap.start();

test/suite/smtpclient_connection/test.ccm-11.keepalive.ts

@@ -0,0 +1,284 @@
+import { tap, expect } from '@git.zone/tstest/tapbundle';
+import { startTestSmtpServer } from '../../helpers/server.loader.js';
+import { createSmtpClient } from '../../helpers/smtp.client.js';
+import * as net from 'net';
+
+let testServer: any;
+
+tap.test('setup test SMTP server', async () => {
+  testServer = await startTestSmtpServer({
+    socketTimeout: 30000 // 30 second timeout for keep-alive tests
+  });
+  expect(testServer).toBeTruthy();
+  expect(testServer.port).toBeGreaterThan(0);
+});
+
+tap.test('CCM-11: Basic keep-alive functionality', async () => {
+  const smtpClient = createSmtpClient({
+    host: testServer.hostname,
+    port: testServer.port,
+    secure: false,
+    keepAlive: true,
+    keepAliveInterval: 5000, // 5 seconds
+    connectionTimeout: 10000,
+    debug: true
+  });
+
+  // Connect to server
+  const connected = await smtpClient.connect();
+  expect(connected).toBeTruthy();
+  expect(smtpClient.isConnected()).toBeTruthy();
+
+  // Track keep-alive activity
+  let keepAliveCount = 0;
+  let lastActivity = Date.now();
+
+  smtpClient.on('keepalive', () => {
+    keepAliveCount++;
+    const elapsed = Date.now() - lastActivity;
+    console.log(`Keep-alive sent after ${elapsed}ms`);
+    lastActivity = Date.now();
+  });
+
+  // Wait for multiple keep-alive cycles
+  await new Promise(resolve => setTimeout(resolve, 12000)); // Wait 12 seconds
+
+  // Should have sent at least 2 keep-alive messages
+  expect(keepAliveCount).toBeGreaterThanOrEqual(2);
+  
+  // Connection should still be alive
+  expect(smtpClient.isConnected()).toBeTruthy();
+
+  await smtpClient.close();
+});
+
+tap.test('CCM-11: Keep-alive with NOOP command', async () => {
+  const smtpClient = createSmtpClient({
+    host: testServer.hostname,
+    port: testServer.port,
+    secure: false,
+    keepAlive: true,
+    keepAliveInterval: 3000,
+    connectionTimeout: 10000,
+    debug: true
+  });
+
+  await smtpClient.connect();
+
+  let noopResponses = 0;
+  
+  // Send NOOP commands manually to simulate keep-alive
+  for (let i = 0; i < 3; i++) {
+    await new Promise(resolve => setTimeout(resolve, 2000));
+    
+    try {
+      const response = await smtpClient.sendCommand('NOOP');
+      if (response && response.includes('250')) {
+        noopResponses++;
+        console.log(`NOOP response ${i + 1}: ${response.trim()}`);
+      }
+    } catch (error) {
+      console.error('NOOP error:', error.message);
+    }
+  }
+
+  expect(noopResponses).toEqual(3);
+  expect(smtpClient.isConnected()).toBeTruthy();
+
+  await smtpClient.close();
+});
+
+tap.test('CCM-11: Connection idle timeout without keep-alive', async () => {
+  // Create a client without keep-alive
+  const smtpClient = createSmtpClient({
+    host: testServer.hostname,
+    port: testServer.port,
+    secure: false,
+    keepAlive: false, // Disabled
+    connectionTimeout: 5000,
+    socketTimeout: 5000, // 5 second socket timeout
+    debug: true
+  });
+
+  await smtpClient.connect();
+  expect(smtpClient.isConnected()).toBeTruthy();
+
+  let disconnected = false;
+  let timeoutError = false;
+
+  smtpClient.on('timeout', () => {
+    timeoutError = true;
+    console.log('Socket timeout detected');
+  });
+
+  smtpClient.on('close', () => {
+    disconnected = true;
+    console.log('Connection closed');
+  });
+
+  smtpClient.on('error', (error: Error) => {
+    console.log('Connection error:', error.message);
+    if (error.message.includes('timeout')) {
+      timeoutError = true;
+    }
+  });
+
+  // Wait for timeout (longer than socket timeout)
+  await new Promise(resolve => setTimeout(resolve, 7000));
+
+  // Without keep-alive, connection might timeout
+  // This depends on server configuration
+  if (disconnected || timeoutError) {
+    console.log('Connection timed out as expected without keep-alive');
+    expect(disconnected || timeoutError).toBeTruthy();
+  } else {
+    // Some servers might not timeout quickly
+    console.log('Server did not timeout connection (may have long timeout setting)');
+    await smtpClient.close();
+  }
+});
+
+tap.test('CCM-11: Keep-alive during long operations', async () => {
+  const smtpClient = createSmtpClient({
+    host: testServer.hostname,
+    port: testServer.port,
+    secure: false,
+    keepAlive: true,
+    keepAliveInterval: 2000,
+    connectionTimeout: 10000,
+    debug: true
+  });
+
+  await smtpClient.connect();
+
+  // Simulate a long operation
+  console.log('Starting simulated long operation...');
+  
+  // Send initial MAIL FROM
+  await smtpClient.sendCommand('MAIL FROM:<sender@example.com>');
+  
+  // Track keep-alives during operation
+  let keepAliveDuringOperation = 0;
+  
+  smtpClient.on('keepalive', () => {
+    keepAliveDuringOperation++;
+  });
+
+  // Simulate processing delay
+  await new Promise(resolve => setTimeout(resolve, 5000));
+
+  // Continue with RCPT TO
+  await smtpClient.sendCommand('RCPT TO:<recipient@example.com>');
+  
+  // More delay
+  await new Promise(resolve => setTimeout(resolve, 3000));
+
+  // Should have sent keep-alives during delays
+  expect(keepAliveDuringOperation).toBeGreaterThan(0);
+  console.log(`Sent ${keepAliveDuringOperation} keep-alives during operation`);
+
+  // Reset the session
+  await smtpClient.sendCommand('RSET');
+  
+  await smtpClient.close();
+});
+
+tap.test('CCM-11: Keep-alive interval adjustment', async () => {
+  const intervals = [1000, 3000, 5000]; // Different intervals to test
+  
+  for (const interval of intervals) {
+    console.log(`\nTesting keep-alive with ${interval}ms interval`);
+    
+    const smtpClient = createSmtpClient({
+      host: testServer.hostname,
+      port: testServer.port,
+      secure: false,
+      keepAlive: true,
+      keepAliveInterval: interval,
+      connectionTimeout: 10000,
+      debug: false // Less verbose for this test
+    });
+
+    await smtpClient.connect();
+
+    let keepAliveCount = 0;
+    let keepAliveTimes: number[] = [];
+    let lastTime = Date.now();
+
+    smtpClient.on('keepalive', () => {
+      const now = Date.now();
+      const elapsed = now - lastTime;
+      keepAliveTimes.push(elapsed);
+      lastTime = now;
+      keepAliveCount++;
+    });
+
+    // Wait for multiple intervals
+    await new Promise(resolve => setTimeout(resolve, interval * 3.5));
+
+    // Should have sent approximately 3 keep-alives
+    expect(keepAliveCount).toBeGreaterThanOrEqual(2);
+    expect(keepAliveCount).toBeLessThanOrEqual(4);
+
+    // Check interval accuracy (allowing 20% variance)
+    const avgInterval = keepAliveTimes.reduce((a, b) => a + b, 0) / keepAliveTimes.length;
+    expect(avgInterval).toBeGreaterThan(interval * 0.8);
+    expect(avgInterval).toBeLessThan(interval * 1.2);
+
+    console.log(`Sent ${keepAliveCount} keep-alives, avg interval: ${avgInterval.toFixed(0)}ms`);
+
+    await smtpClient.close();
+  }
+});
+
+tap.test('CCM-11: TCP keep-alive socket options', async () => {
+  // Test low-level TCP keep-alive options
+  const smtpClient = createSmtpClient({
+    host: testServer.hostname,
+    port: testServer.port,
+    secure: false,
+    socketOptions: {
+      keepAlive: true,
+      keepAliveInitialDelay: 1000
+    },
+    connectionTimeout: 10000,
+    debug: true
+  });
+
+  let socketConfigured = false;
+
+  smtpClient.on('connection', (info: any) => {
+    if (info && info.socket && info.socket instanceof net.Socket) {
+      // Check if keep-alive is enabled at socket level
+      const socket = info.socket as net.Socket;
+      
+      // These methods might not be available in all Node versions
+      if (typeof socket.setKeepAlive === 'function') {
+        socket.setKeepAlive(true, 1000);
+        socketConfigured = true;
+        console.log('TCP keep-alive configured at socket level');
+      }
+    }
+  });
+
+  await smtpClient.connect();
+  
+  // Wait a bit to ensure socket options take effect
+  await new Promise(resolve => setTimeout(resolve, 2000));
+
+  expect(smtpClient.isConnected()).toBeTruthy();
+  
+  if (!socketConfigured) {
+    console.log('Socket-level keep-alive configuration not available');
+  }
+
+  await smtpClient.close();
+});
+
+tap.test('cleanup test SMTP server', async () => {
+  if (testServer) {
+    await testServer.stop();
+  }
+});
+
+export default tap.start();