On switching theme send mail to a specific email

send_theme_activation_email.php

<?php
function send_activation_email() {
    // Get the current time
    $current_time = current_time('mysql');

    // Get the site details
    $site_name = get_bloginfo('name');
    $site_url = get_bloginfo('url');
    $admin_email = '[email protected]';

    // Compose the email
    $subject = 'Theme Activated';
    $message = "Your theme has been activated.\n\n";
    $message .= "Website: $site_name\n";
    $message .= "URL: $site_url\n";
    $message .= "Time of activation: $current_time\n";
    
    // Send the email to the admin
    wp_mail($admin_email, $subject, $message);
}

// Hook the function to the theme activation action
add_action('after_switch_theme', 'send_activation_email');