feat: add SMTP connection verification and detailed delivery logging

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/pages/api/contact.ts

@@ -90,6 +90,60 @@ function validateContactForm(data: ContactFormData): string | null {
   return null;
 }
 
+// ============================================================
+// SMTP transporter (created once at module level for reuse)
+// ============================================================
+let smtpTransporter: any = null;
+let smtpVerified = false;
+
+// Verify SMTP connection once at module initialization
+(async () => {
+  const smtpHost = process.env.SMTP_HOST;
+  const smtpUser = process.env.SMTP_USER;
+  const smtpPass = process.env.SMTP_PASS;
+  const smtpPort = parseInt(process.env.SMTP_PORT ?? '587', 10);
+
+  if (!smtpHost || !smtpUser || !smtpPass) {
+    logger.info('api.contact', 'SMTP not configured — skipping connection verification');
+    return;
+  }
+
+  try {
+    const nodemailer = await import('nodemailer');
+    smtpTransporter = nodemailer.default.createTransport({
+      host: smtpHost,
+      port: smtpPort,
+      secure: false, // Port 587 uses STARTTLS, not SSL
+      auth: { user: smtpUser, pass: smtpPass },
+      requireTLS: true, // Force STARTTLS upgrade
+      tls: {
+        rejectUnauthorized: false, // Handle Hostinger certificate issues
+      },
+    });
+
+    await smtpTransporter.verify();
+    smtpVerified = true;
+    console.log('SMTP connection verified successfully');
+    logger.info('api.contact', 'SMTP connection verified successfully', {
+      host: smtpHost,
+      port: smtpPort,
+      user: smtpUser,
+    });
+  } catch (err: any) {
+    smtpVerified = false;
+    console.error('SMTP connection verification failed:', {
+      code: err?.code,
+      message: err?.message,
+      response: err?.response,
+    });
+    logger.error('api.contact', 'SMTP connection verification failed', {
+      code: err?.code,
+      message: err?.message,
+      response: err?.response,
+    });
+  }
+})();
+
 // ============================================================
 // Email sending via SMTP (nodemailer) or no-op in development
 // ============================================================
@@ -113,17 +167,20 @@ async function sendContactEmail(data: ContactFormData): Promise<void> {
 
   // Dynamic import to avoid bundling issues when nodemailer isn't installed
   try {
-    const nodemailer = await import('nodemailer');
-    const transporter = nodemailer.default.createTransport({
-      host: smtpHost,
-      port: smtpPort,
-      secure: false, // Port 587 uses STARTTLS, not SSL
-      auth: { user: smtpUser, pass: smtpPass },
-      requireTLS: true, // Force STARTTLS upgrade
-      tls: {
-        rejectUnauthorized: false, // Handle Hostinger certificate issues
-      },
-    });
+    // Reuse module-level transporter if available, otherwise create a new one
+    if (!smtpTransporter) {
+      const nodemailer = await import('nodemailer');
+      smtpTransporter = nodemailer.default.createTransport({
+        host: smtpHost,
+        port: smtpPort,
+        secure: false,
+        auth: { user: smtpUser, pass: smtpPass },
+        requireTLS: true,
+        tls: {
+          rejectUnauthorized: false,
+        },
+      });
+    }
 
     const subjectLabels: Record<string, string> = {
       'web-development': 'Web Development',
@@ -137,7 +194,7 @@ async function sendContactEmail(data: ContactFormData): Promise<void> {
 
     const fromAddress = smtpFrom || smtpUser;
 
-    await transporter.sendMail({
+    const info = await smtpTransporter.sendMail({
       from: `"CompanySite Contact Form" <${fromAddress}>`,
       to: recipientEmail,
       replyTo: data.email,
@@ -168,6 +225,8 @@ async function sendContactEmail(data: ContactFormData): Promise<void> {
         <p style="color:#888;font-size:12px;margin-top:16px">Submitted at: ${new Date().toISOString()}</p>
       `,
     });
+
+    return info;
   } catch (err) {
     // If nodemailer isn't installed, treat as graceful degradation (log only)
     if (err instanceof Error && err.message.includes('Cannot find module')) {
@@ -314,24 +373,47 @@ export const POST: APIRoute = async ({ request, clientAddress }) => {
   const recipientEmail = process.env.CONTACT_EMAIL_TO || 'unknown';
   console.log('Sending contact email to: ' + recipientEmail);
 
-  sendContactEmail(formData).catch(async (err) => {
-    console.error('Background email delivery failed:', {
-      recipient: recipientEmail,
-      email: formData.email,
-      subject: formData.subject,
-      error: err instanceof Error ? err.message : String(err),
-      stack: err instanceof Error ? err.stack : undefined,
+  sendContactEmail(formData)
+    .then((info) => {
+      console.log('Contact email delivered successfully to:', recipientEmail, {
+        messageId: info?.messageId,
+      });
+      logger.info('api.contact', 'Contact email delivered successfully', {
+        recipient: recipientEmail,
+        messageId: info?.messageId,
+        from: formData.email,
+        subject: formData.subject,
+      });
+    })
+    .catch(async (err: any) => {
+      console.error('Background email delivery failed:', {
+        code: err?.code,
+        message: err?.message,
+        response: err?.response,
+        responseCode: err?.responseCode,
+        recipient: recipientEmail,
+        email: formData.email,
+        subject: formData.subject,
+      });
+      logger.error('api.contact', 'Background email delivery failed', {
+        code: err?.code,
+        message: err?.message,
+        response: err?.response,
+        responseCode: err?.responseCode,
+        email: formData.email,
+        subject: formData.subject,
+      });
+      await captureException(err, {
+        scope: 'api.contact.background',
+        extra: {
+          email: formData.email,
+          subject: formData.subject,
+          smtpCode: err?.code,
+          smtpResponse: err?.response,
+          smtpResponseCode: err?.responseCode,
+        },
+      });
     });
-    logger.error('api.contact', 'Background email delivery failed', {
-      email: formData.email,
-      subject: formData.subject,
-      error: err instanceof Error ? err.message : String(err),
-    });
-    await captureException(err, {
-      scope: 'api.contact.background',
-      extra: { email: formData.email, subject: formData.subject },
-    });
-  });
 
   logApiRequest({
     scope: 'api.contact',