feat(storage): add comprehensive tests for StorageManager with memory, filesystem, and custom function backends

feat(email): implement EmailSendJob class for robust email delivery with retry logic and MX record resolution

feat(mail): restructure mail module exports for simplified access to core and delivery functionalities

test/suite/smtpclient_rfc-compliance/test.crfc-02.esmtp-compliance.ts

@@ -0,0 +1,77 @@
+import { expect, tap } from '@git.zone/tstest/tapbundle';
+import { createTestServer } from '../../helpers/server.loader.ts';
+import { createTestSmtpClient } from '../../helpers/smtp.client.ts';
+import { Email } from '../../../ts/mail/core/classes.email.ts';
+
+tap.test('CRFC-02: Basic ESMTP Compliance', async () => {
+  console.log('\n📧 Testing SMTP Client ESMTP Compliance');
+  console.log('=' .repeat(60));
+
+  const testServer = await createTestServer({});
+
+  try {
+    const smtpClient = createTestSmtpClient({
+      host: testServer.hostname,
+      port: testServer.port
+    });
+
+    console.log('\nTest 1: Basic EHLO negotiation');
+    const email1 = new Email({
+      from: 'sender@example.com',
+      to: ['recipient@example.com'],
+      subject: 'ESMTP test',
+      text: 'Testing ESMTP'
+    });
+
+    const result1 = await smtpClient.sendMail(email1);
+    console.log('  ✓ EHLO negotiation successful');
+    expect(result1).toBeDefined();
+
+    console.log('\nTest 2: Multiple recipients');
+    const email2 = new Email({
+      from: 'sender@example.com',
+      to: ['recipient1@example.com', 'recipient2@example.com'],
+      cc: ['cc@example.com'],
+      bcc: ['bcc@example.com'],
+      subject: 'Multiple recipients',
+      text: 'Testing multiple recipients'
+    });
+
+    const result2 = await smtpClient.sendMail(email2);
+    console.log('  ✓ Multiple recipients handled');
+    expect(result2).toBeDefined();
+
+    console.log('\nTest 3: UTF-8 content');
+    const email3 = new Email({
+      from: 'sender@example.com',
+      to: ['recipient@example.com'],
+      subject: 'UTF-8: café ☕ 测试',
+      text: 'International text: émojis 🎉, 日本語',
+      html: '<p>HTML: <strong>Zürich</strong></p>'
+    });
+
+    const result3 = await smtpClient.sendMail(email3);
+    console.log('  ✓ UTF-8 content accepted');
+    expect(result3).toBeDefined();
+
+    console.log('\nTest 4: Long headers');
+    const longSubject = 'This is a very long subject line that exceeds 78 characters and should be properly folded according to RFC 2822';
+    const email4 = new Email({
+      from: 'sender@example.com',
+      to: ['recipient@example.com'],
+      subject: longSubject,
+      text: 'Testing header folding'
+    });
+
+    const result4 = await smtpClient.sendMail(email4);
+    console.log('  ✓ Long headers handled');
+    expect(result4).toBeDefined();
+
+    console.log('\n✅ CRFC-02: ESMTP compliance tests completed');
+
+  } finally {
+    testServer.server.close();
+  }
+});
+
+tap.start();