Polar SMTP Mailer

A lightweight, open-source WordPress SMTP plugin

Reliable email delivery for WordPress.
Features email logging, queue management, backup failover, and a modern dashboard.

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🏆 Why Choose Polar SMTP Mailer?

Polar SMTP Mailer provides a complete email delivery solution:

• ✅ 100% Free & Open Source - No premium tiers or feature locks
• ✅ Email Logging - Complete history with search, filter, export
• ✅ Backup SMTP Failover - Automatic switch when primary fails
• ✅ Email Queue - Background processing with priority & retry
• ✅ 15+ Provider Presets - Gmail, Outlook, SendGrid, Mailgun, and more
• ✅ Password Encryption - AES-256-CBC with WordPress salts
• ✅ GDPR Privacy Tools - Exporter, eraser, anonymization
• ✅ Modern Dashboard - Statistics, charts, quick actions
• ✅ Self-Healing Database - Automatic table creation & repair
• ✅ Clean Uninstall Option - Remove all data on deletion

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✨ Features at a Glance

Feature	Description
📧 15+ SMTP Providers	Gmail, Outlook, Yahoo, SendGrid, Mailgun, Amazon SES, Hostinger & more
📊 Email Logging	Complete history with search, filter, export (CSV/JSON)
🔄 Email Queue	Background processing with priority & retry logic
🔒 Backup SMTP	Automatic failover when primary fails
🛡️ Enterprise Security	AES-256 encryption, rate limiting, CSRF protection
🔐 GDPR Compliant	Privacy exporter, eraser, and anonymization
🎨 Modern Dashboard	Statistics, charts, and quick actions
♿ Accessible	WCAG AA compliant, screen reader friendly

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📧 SMTP Configuration

Supported Providers

Provider	Host	Port (TLS)	Port (SSL)
Gmail / Google Workspace	smtp.gmail.com	587	465
Outlook / Microsoft 365	smtp.office365.com	587	-
Yahoo Mail	smtp.mail.yahoo.com	587	465
Zoho Mail	smtp.zoho.com	587	465
Hostinger	smtp.hostinger.com	465 (SSL)	465
SendGrid	smtp.sendgrid.net	587	465
Mailgun	smtp.mailgun.org	587	465
Amazon SES	email-smtp.[region].amazonaws.com	587	465
Brevo (Sendinblue)	smtp-relay.brevo.com	587	465
Postmark	smtp.postmarkapp.com	587	465
SparkPost	smtp.sparkpostmail.com	587	-
SMTP.com	send.smtp.com	587	465
Elastic Email	smtp.elasticemail.com	2525	-
Mailjet	in-v3.mailjet.com	587	465
Pepipost (Netcore)	smtp.pepipost.com	587	465

Encryption Options

Type	Port	Recommendation
TLS	587	✅ Recommended (STARTTLS)
SSL	465	Good alternative
None	25	⚠️ Not recommended

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📊 Email Logging

• Complete History - Track all sent, failed, and queued emails
• View Details - Full email content, headers, CC/BCC, attachments
• Search & Filter - Find by recipient, subject, status, or date range
• One-Click Actions - View, Resend, Delete individual logs
• Bulk Operations - Delete multiple logs at once
• Export - Download as CSV or JSON
• Auto Cleanup - Configurable retention (default: 30 days)

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🔄 Email Queue System

Feature	Description
Background Processing	Via WP-Cron, no server impact
Batch Size	Configurable (default: 10)
Processing Interval	Configurable (default: 5 min)
Priority Support	1-10 scale for urgent emails
Retry Logic	Up to 3 attempts on failure
Lock Mechanism	Prevents duplicate processing
Test Bypass	Test emails skip queue

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🛡️ Security

Feature	Implementation
Password Encryption	AES-256-CBC with WordPress AUTH_KEY
CSRF Protection	Nonces on all forms and AJAX
Authorization	manage_options capability required
Rate Limiting	5 test emails per 10 minutes
Input Sanitization	All inputs sanitized
Output Escaping	All output escaped (XSS prevention)
SQL Injection	Prepared statements everywhere

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🔐 Privacy & GDPR

• ✅ WordPress Privacy Exporter integration
• ✅ WordPress Privacy Eraser integration
• ✅ Email anonymization option
• ✅ Content exclusion from logs
• ✅ Auto-suggested privacy policy text
• ✅ Configurable data retention

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🎨 Modern Dashboard

• 📈 Email statistics (Today, Week, Month, All-time)
• 📊 Visual charts with daily trends
• ⚡ Quick actions (Test email, View logs, Settings)
• 🔌 Connection health indicator
• 📬 Real-time queue counter
• 📱 Fully responsive design

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📥 Installation

From GitHub

# Download and extract to wp-content/plugins/
git clone https://github.com/boopathirbk/polar-smtp-mailer.git

From WordPress

1. Plugins → Add New → Upload Plugin
2. Upload the ZIP file
3. Activate and configure at Polar SMTP → Settings

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⚙️ Quick Setup

1. Navigate to Polar SMTP → Settings
2. Select your SMTP provider from dropdown
3. Enter your credentials (username/password)
4. Click Test Connection to verify
5. Send a test email to confirm delivery
6. Save Settings

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🔧 Requirements

Requirement	Version
WordPress	6.0+
PHP	7.4+
MySQL	5.6+ / MariaDB 10.0+
OpenSSL	Required for encryption

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🧑‍💻 Developer Hooks

Add Custom Provider

add_filter( 'psm_smtp_providers', function( $providers ) {
    $providers['my_provider'] = array(
        'name'       => 'My Custom Provider',
        'host'       => 'smtp.example.com',
        'port'       => 587,
        'encryption' => 'tls',
        'auth'       => true,
    );
    return $providers;
});

Bypass Queue for Urgent Emails

add_filter( 'psm_bypass_queue', function( $bypass, $atts ) {
    if ( strpos( $atts['subject'], 'Urgent' ) !== false ) {
        return true; // Send immediately
    }
    return $bypass;
}, 10, 2 );

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📸 Screenshots

Dashboard	Settings

Email Logs	Test Email

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📝 Changelog

1.0.5 (2025-12-17)

• Compliance: Removed promotional/comparative language from readme files.
• Compliance: Added External Services section for SMTP provider documentation.

1.0.4 (2025-12-11)

• Compliance: Fixed global variable naming conventions in admin views.
• Compliance: Fixed hook naming conventions.
• UI: Enhanced email log modal with From Email tracking and grid layout.
• UI: Improved modal responsiveness for mobile devices.
• Fix: Backup SMTP connection test and result styling.
• Fix: Uninstall cleanup.

1.0.3 (2025-12-10)

• Removed debug logging for compliance.

1.0.2 (2025-12-10)

• Fixed HTML email display in log viewer.
• Fixed empty recipient validation in queue.
• Improved PHP 8.2 compatibility.

1.0.1 (2025-12-10)

• Security fixes (Encryption, SQL prep).
• Fixed race condition in queue processing.
• TLS 1.2/1.3 support.

1.0.0 (2025-12-06)

Initial Release:

• SMTP configuration with 15+ provider presets
• Email logging with View, Resend, Delete actions
• Email queue with background processing
• Backup SMTP failover
• GDPR-compliant privacy features
• Modern admin dashboard with statistics
• AES-256-CBC password encryption
• Rate limiting and security features
• Hostinger SMTP sender fix
• Self-healing database
• Clean uninstall option
• Full i18n support

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🤝 Contributing

1. Fork the repository
2. Create feature branch (git checkout -b feature/Amazing)
3. Commit changes (git commit -m 'Add Amazing Feature')
4. Push to branch (git push origin feature/Amazing)
5. Open a Pull Request

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📄 License

GPL v2 or later - see LICENSE for details.

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👨‍💻 Author

Boopathi R.

• LinkedIn: @boopathirb
• GitHub: @boopathirbk

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☕ Support This Project

If you find this plugin useful, consider buying me a coffee!

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Made with ❤️ for the WordPress community