fix: Support Exchange servers without authentication

- Make email authentication optional in transporter config
- Only add auth object if both username and password are provided
- Update initialization to only require SMTP_HOST
- Add logging to show whether auth is enabled
- Update documentation with no-auth configuration examples
- Fix "Unrecognized authentication type" error for open relays

Exchange servers configured as internal relays often don't
require authentication. This fix allows using them by leaving
SMTP_USER and SMTP_PASS empty in the .env file.

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

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

EMAIL_CONFIGURATION.md

@@ -8,6 +8,7 @@ MinIO WebUI supports email notifications for storage reports. This guide explain
 
 Configure these variables in your `.env` file:
 
+### With Authentication (Most servers)
 ```bash
 # SMTP Server Configuration
 SMTP_HOST=your-exchange-server.com
@@ -24,6 +25,24 @@ REPORT_RECIPIENT=admin@yourdomain.com
 REPORT_SCHEDULE=0 0 * * 1  # Every Monday at midnight
 ```
 
+### Without Authentication (Open Relay/Internal Exchange)
+```bash
+# SMTP Server Configuration
+SMTP_HOST=exchange.internal.company.com
+SMTP_PORT=25
+SMTP_SECURE=false
+# Leave SMTP_USER and SMTP_PASS empty or don't include them
+SMTP_USER=
+SMTP_PASS=
+
+# Email Settings
+REPORT_SENDER=minio-reports@yourdomain.com
+REPORT_RECIPIENT=admin@yourdomain.com
+
+# Report Schedule (cron format)
+REPORT_SCHEDULE=0 0 * * 1  # Every Monday at midnight
+```
+
 ## Port and Security Settings
 
 ### Port 25 (No TLS/SSL)
@@ -70,11 +89,13 @@ SMTP_SECURE=true
 
 ### Authentication Failed
 
-**Error**: `Invalid login`
+**Error**: `Invalid login` or `Unrecognized authentication type`
 
 **Solution**:
-1. Verify SMTP_USER and SMTP_PASS are correct
-2. For Exchange, use either:
+1. If your Exchange server doesn't require authentication (internal relay):
+   - Leave `SMTP_USER` and `SMTP_PASS` empty in your .env file
+   - Or remove these variables entirely
+2. If authentication is required, verify credentials:
    - Username only: `username`
    - Domain\Username: `DOMAIN\\username`
    - Email format: `username@domain.com`

backend/src/services/report.service.js

@@ -10,23 +10,19 @@ class ReportService {
     this.transporter = null;
     this.scheduledTask = null;
     
-    if (config.email.host && config.email.auth.user) {
+    if (config.email.host) {
       this.initializeMailer();
       this.setupSchedule();
     } else {
-      logger.warn('Email configuration missing. Report scheduling disabled.');
+      logger.warn('Email host not configured. Report scheduling disabled.');
     }
   }
 
   initializeMailer() {
-    this.transporter = nodemailer.createTransport({
+    const transportConfig = {
       host: config.email.host,
       port: config.email.port,
       secure: config.email.secure,
-      auth: {
-        user: config.email.auth.user,
-        pass: config.email.auth.pass,
-      },
       // For Exchange Server on port 25 without TLS
       tls: {
         rejectUnauthorized: false, // Accept self-signed certificates
@@ -36,7 +32,20 @@ class ReportService {
       // Disable STARTTLS for port 25 if not using secure
       requireTLS: config.email.secure,
       ignoreTLS: config.email.port === 25 && !config.email.secure,
-    });
+    };
+
+    // Only add auth if username and password are provided
+    if (config.email.auth.user && config.email.auth.pass) {
+      transportConfig.auth = {
+        user: config.email.auth.user,
+        pass: config.email.auth.pass,
+      };
+      logger.info('Email configured with authentication');
+    } else {
+      logger.info('Email configured without authentication (open relay)');
+    }
+
+    this.transporter = nodemailer.createTransport(transportConfig);
 
     // Verify connection
     this.transporter.verify((error) => {