Email Logger MU Plugin for WordPress Multisite

email-logger-multisite.php

<?php
/**
 * Plugin Name: Network Email Logger
 * Description: Logs all emails sent across the network
 * Network: true
 */

add_filter('wp_mail', 'network_log_wp_mail', 999);
function network_log_wp_mail($args) {
    // Store in network option (available across all sites)
    $emails = get_site_option('network_emails_log', array());
    
    $email_data = array(
        'time' => current_time('mysql'),
        'to' => $args['to'],
        'subject' => $args['subject'],
        'message' => $args['message'],
        'headers' => $args['headers'] ?? '',
        'site_id' => get_current_blog_id(),
    );
    
    // Keep last 50 emails
    array_unshift($emails, $email_data);
    $emails = array_slice($emails, 0, 50);
    
    update_site_option('network_emails_log', $emails);
    
    return $args;
}

// Add Network Admin menu to view emails
add_action('network_admin_menu', 'network_email_log_menu');
function network_email_log_menu() {
    add_menu_page(
        'Email Log',
        'Email Log',
        'manage_network',
        'network-email-log',
        'network_email_log_page',
        'dashicons-email'
    );
}

function network_email_log_page() {
    $emails = get_site_option('network_emails_log', array());
    
    echo '<div class="wrap">';
    echo '<h1>Network Email Log</h1>';
    
    if (isset($_POST['clear_log'])) {
        delete_site_option('network_emails_log');
        echo '<div class="notice notice-success"><p>Email log cleared!</p></div>';
        $emails = array();
    }
    
    echo '<form method="post" style="margin-bottom: 20px;">';
    echo '<input type="submit" name="clear_log" class="button" value="Clear Log">';
    echo '</form>';
    
    if (empty($emails)) {
        echo '<p>No emails logged yet.</p>';
    } else {
        foreach ($emails as $email) {
            echo '<div style="border: 1px solid #ccc; padding: 15px; margin-bottom: 20px; background: #f9f9f9;">';
            echo '<p><strong>Time:</strong> ' . esc_html($email['time']) . '</p>';
            echo '<p><strong>Site ID:</strong> ' . esc_html($email['site_id']) . '</p>';
            echo '<p><strong>To:</strong> ' . esc_html(is_array($email['to']) ? implode(', ', $email['to']) : $email['to']) . '</p>';
            echo '<p><strong>Subject:</strong> ' . esc_html($email['subject']) . '</p>';
            echo '<p><strong>Message:</strong></p>';
            echo '<pre style="background: white; padding: 10px; overflow-x: auto;">' . esc_html($email['message']) . '</pre>';
            echo '</div>';
        }
    }
    
    echo '</div>';
}