fix: improve email test endpoint error handling

- Add detailed validation for SMTP configuration
- Add specific error messages for common SMTP issues (connection, auth, network)
- Add logging to help debug email configuration issues
- Check for masked passwords that shouldn't be used for sending
- Parse smtp_port as integer and handle boolean smtp_secure properly

This helps identify the exact cause of email sending failures instead of
generic 500 errors.

🤖 Generated with [Claude Code](https://claude.ai/code)

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

backend/src/routes/adminEmail.js

@@ -112,17 +112,44 @@ router.post('/test', adminAuth, async (req, res) => {
       return res.status(400).json({ error: 'Email configuration not found. Please configure SMTP settings first.' });
     }
 
-    // Create transporter
-    const transporter = nodemailer.createTransport({
+    // Validate SMTP configuration
+    if (!config.smtp_host || !config.smtp_port) {
+      return res.status(400).json({ 
+        error: 'Incomplete email configuration',
+        details: 'SMTP host and port are required'
+      });
+    }
+    
+    // Check if password might be masked (this shouldn't happen when fetching from DB)
+    if (config.smtp_pass === '********') {
+      return res.status(400).json({
+        error: 'Invalid email configuration',
+        details: 'SMTP password appears to be masked. Please reconfigure your email settings.'
+      });
+    }
+
+    // Create transporter with detailed logging
+    const transportConfig = {
       host: config.smtp_host,
-      port: config.smtp_port,
-      secure: config.smtp_secure,
-      auth: config.smtp_user ? {
+      port: parseInt(config.smtp_port),
+      secure: config.smtp_secure === true || config.smtp_secure === 1,
+      auth: config.smtp_user && config.smtp_pass ? {
         user: config.smtp_user,
         pass: config.smtp_pass
-      } : undefined
+      } : undefined,
+      logger: process.env.NODE_ENV === 'development',
+      debug: process.env.NODE_ENV === 'development'
+    };
+
+    console.log('Creating email transporter with config:', {
+      host: transportConfig.host,
+      port: transportConfig.port,
+      secure: transportConfig.secure,
+      auth: transportConfig.auth ? 'configured' : 'none'
     });
 
+    const transporter = nodemailer.createTransport(transportConfig);
+
     // Send test email
     await transporter.sendMail({
       from: `${config.from_name} <${config.from_email}>`,
@@ -145,9 +172,27 @@ router.post('/test', adminAuth, async (req, res) => {
     res.json({ message: 'Test email sent successfully' });
   } catch (error) {
     console.error('Test email error:', error);
+    console.error('Error stack:', error.stack);
+    
+    // Provide more specific error messages
+    let errorMessage = 'Failed to send test email';
+    let details = error.message;
+    
+    if (error.code === 'ECONNREFUSED') {
+      errorMessage = 'Failed to connect to SMTP server';
+      details = 'Please check your SMTP host and port settings';
+    } else if (error.code === 'EAUTH') {
+      errorMessage = 'SMTP authentication failed';
+      details = 'Please check your SMTP username and password';
+    } else if (error.code === 'ESOCKET') {
+      errorMessage = 'Network error';
+      details = 'Could not establish connection to SMTP server';
+    }
+    
     res.status(500).json({ 
-      error: 'Failed to send test email',
-      details: error.message 
+      error: errorMessage,
+      details: details,
+      code: error.code
     });
   }
 });