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Email Subscription Box

A lightweight WordPress plugin that provides a simple email subscription form with local storage, AJAX submission, and CSV export functionality.

Single File v1.0.1 Updated 3 days ago
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YT Email Subscription Box

A lightweight WordPress plugin that provides a simple email subscription form with local storage, AJAX submission, and CSV export functionality.

Features

  • Simple Subscription Form - Clean, responsive opt-in form
  • Local Storage - Stores subscribers in custom database table
  • AJAX Submission - No page reload required
  • Duplicate Prevention - Automatically prevents duplicate emails
  • CSV Export - Export all subscribers to CSV file
  • Confirmation Emails - Optional welcome emails for new subscribers
  • Admin Dashboard - View and manage subscribers
  • IP Tracking - Records subscriber IP addresses
  • Pagination - Admin list with 20 subscribers per page
  • Shortcode Ready - Easy integration with [yt_subscribe_box]
  • WPCS Compliant - Follows WordPress Coding Standards
  • Secure - Nonce verification, sanitization, and escaping

Installation

  1. Upload the plugin folder to /wp-content/plugins/
  2. Activate the plugin through the 'Plugins' menu in WordPress
  3. Go to Subscribers → Settings to configure options
  4. Use the shortcode [yt_subscribe_box] in any post or page

File Structure

yt-email-subscription-box/
├── class-yt-email-subscription-box.php  # Main plugin file (505 lines)
├── assets/
│   ├── css/
│   │   └── style.css                     # Frontend styles
│   └── js/
│       └── script.js                     # AJAX functionality
└── README.md                             # Documentation

Usage

Basic Shortcode

[yt_subscribe_box]

Shortcode with Attributes

[yt_subscribe_box title="Join Our Newsletter" button_text="Subscribe Now"]

Available Attributes

Attribute Description Default
title Form heading "Subscribe to Our Newsletter"
button_text Submit button text "Subscribe"
class Additional CSS class ""

Example Usage in Posts

<!-- Basic usage -->
[yt_subscribe_box]

<!-- Custom title -->
[yt_subscribe_box title="Get Weekly Updates!"]

<!-- Custom button -->
[yt_subscribe_box button_text="Join Now"]

<!-- Custom styling -->
[yt_subscribe_box class="my-custom-class"]

<!-- All attributes -->
[yt_subscribe_box title="Newsletter Signup" button_text="Subscribe" class="sidebar-form"]

Template File Usage

<?php echo do_shortcode( '[yt_subscribe_box title="Subscribe"]' ); ?>

Admin Features

Subscribers List

Access via Subscribers menu in WordPress admin.

Features:

  • View all subscribers with email, IP, and date
  • Pagination (20 per page)
  • Total subscriber count
  • One-click CSV export

Settings Page

Access via Subscribers → Settings.

Options:

  • Send Confirmation Email - Enable/disable welcome emails
  • Confirmation Subject - Email subject line
  • Confirmation Message - Email body (supports {email} placeholder)

CSV Export

  1. Go to Subscribers page
  2. Click Export to CSV button
  3. File downloads as subscribers-YYYY-MM-DD.csv

CSV format:

ID,Email,IP Address,Subscribed At
1,user@example.com,192.168.1.1,2025-01-01 12:00:00

Database Schema

The plugin creates a custom table: wp_yt_email_subscribers

Table Structure

Column Type Description
id bigint(20) Primary key, auto-increment
email varchar(100) Subscriber email (unique)
ip_address varchar(45) Subscriber IP address
subscribed_at datetime Subscription date and time

SQL Query

CREATE TABLE wp_yt_email_subscribers (
    id bigint(20) unsigned NOT NULL AUTO_INCREMENT,
    email varchar(100) NOT NULL,
    ip_address varchar(45) NOT NULL,
    subscribed_at datetime NOT NULL,
    PRIMARY KEY (id),
    UNIQUE KEY email (email)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;

Confirmation Email

Configuration

  1. Go to Subscribers → Settings
  2. Check Send Confirmation Email
  3. Set Confirmation Subject: Welcome to our newsletter!
  4. Set Confirmation Message: Thank you for subscribing! Your email: {email}

Email Placeholder

Use {email} in your message to include the subscriber's email address.

Example:

Hello!

Thank you for subscribing with {email}.

We're excited to have you on board!

Best regards,
The Team

Security Features

✅ Implemented Security Measures:

  • Nonce Verification - AJAX requests verified with nonces
  • Email Validation - Server-side email validation with is_email()
  • Sanitization - All inputs sanitized (sanitize_email(), sanitize_text_field())
  • Escaping - All outputs escaped (esc_html(), esc_attr(), esc_url())
  • Capability Checks - Admin functions require manage_options
  • Prepared Statements - SQL queries use $wpdb->prepare()
  • Duplicate Prevention - Unique key constraint on email column
  • IP Sanitization - IP addresses properly sanitized
  • Direct Access Prevention - File access protection with WPINC check

AJAX Flow

  1. User enters email in form
  2. JavaScript validates email format
  3. Form submission prevented, AJAX request sent
  4. PHP validates email, checks for duplicates
  5. Email inserted into database
  6. Optional confirmation email sent
  7. Success/error message displayed
  8. Form cleared on success

Hooks & Filters

Available Hooks

While the plugin doesn't expose custom hooks in this version, you can use WordPress core hooks:

// Modify confirmation email
add_filter( 'wp_mail', 'custom_yt_esb_email', 10, 1 );
function custom_yt_esb_email( $args ) {
    // Modify email arguments
    return $args;
}

// Run code after plugin activation
add_action( 'activated_plugin', 'custom_yt_esb_activated', 10, 2 );
function custom_yt_esb_activated( $plugin, $network_wide ) {
    if ( $plugin === 'yt-email-subscription-box/class-yt-email-subscription-box.php' ) {
        // Custom activation code
    }
}

Customization

CSS Customization

Override default styles in your theme:

/* Custom wrapper styles */
.yt-esb-wrapper {
    background: #ffffff;
    border: 2px solid #000;
}

/* Custom button styles */
.yt-esb-button {
    background-color: #ff5722;
}

.yt-esb-button:hover {
    background-color: #e64a19;
}

/* Custom input styles */
.yt-esb-input {
    border-color: #000;
}

JavaScript Customization

Extend the form behavior:

jQuery(document).ready(function($) {
    // Add custom validation
    $('.yt-esb-form').on('submit', function(e) {
        const email = $(this).find('.yt-esb-input').val();

        // Custom validation logic
        if (email.includes('spam')) {
            e.preventDefault();
            alert('Invalid email domain');
            return false;
        }
    });

    // Track subscription attempts
    $('.yt-esb-form').on('submit', function() {
        console.log('Subscription attempt:', new Date());
    });
});

Uninstall

The plugin provides a clean uninstall process:

  1. Deactivate the plugin
  2. Delete the plugin files
  3. Database table and options are automatically removed

What Gets Deleted

  • Custom database table: wp_yt_email_subscribers
  • Plugin options: yt_esb_options
  • All subscriber data
  • All settings

Development

Constants Defined

YT_ESB_VERSION  // Plugin version: 1.0.0
YT_ESB_BASENAME // Plugin basename
YT_ESB_PATH     // Plugin directory path
YT_ESB_URL      // Plugin directory URL

Main Class Methods

Method Description
get_instance() Get singleton instance
init_hooks() Register WordPress hooks
load_textdomain() Load translations
enqueue_scripts() Enqueue frontend CSS/JS
admin_enqueue_scripts() Enqueue admin CSS
add_admin_menu() Add admin menu pages
register_settings() Register plugin settings
sanitize_options() Sanitize settings input
render_admin_page() Display subscribers list
render_settings_page() Display settings page
handle_csv_export() Export subscribers to CSV
render_shortcode() Render subscription form
handle_subscription() Process AJAX subscription
send_confirmation_email() Send welcome email
get_user_ip() Get subscriber IP address
activate() Plugin activation
deactivate() Plugin deactivation

Troubleshooting

Form Not Submitting

  1. Check JavaScript console for errors
  2. Ensure jQuery is loaded
  3. Verify AJAX URL is correct
  4. Check nonce verification

Emails Not Sending

  1. Verify Send Confirmation Email is enabled
  2. Check WordPress email configuration
  3. Install SMTP plugin (e.g., WP Mail SMTP)
  4. Check spam folder

Duplicate Email Error

This is expected behavior. The plugin prevents duplicate subscriptions.

CSV Export Not Working

  1. Verify you have manage_options capability
  2. Check file permissions
  3. Ensure nonce is valid
  4. Check for PHP errors in debug log

Subscribers Not Showing

  1. Check database table was created on activation
  2. Verify table name: wp_yt_email_subscribers
  3. Check database permissions
  4. Re-activate the plugin

Performance

  • Database: Single table with indexed email column
  • AJAX: Asynchronous form submission
  • Assets: Minified CSS/JS (optional)
  • Queries: Optimized with pagination
  • Caching: Compatible with caching plugins

Browser Support

  • Chrome 90+
  • Firefox 88+
  • Safari 14+
  • Edge 90+
  • Opera 76+

Requirements

  • WordPress: 5.8 or higher
  • PHP: 7.4 or higher
  • MySQL: 5.6 or higher
  • jQuery: Included with WordPress

Changelog

1.0.0 (2025-01-18)

  • Initial release
  • Email subscription form with AJAX
  • Local database storage
  • CSV export functionality
  • Confirmation email support
  • Admin dashboard
  • WPCS compliant code

License

GPL v2 or later

Credits

Built following WordPress Plugin Handbook and WPCS guidelines.

Support

For issues and feature requests, please visit:

Author

Krasen Slavov

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