PHP SMTP Mailer Kit

A lightweight, ready-to-integrate PHP email kit built on top of PHPMailer. Includes a Contact Us page and a Subscribe / Newsletter page — both fully functional, responsive, and easy to customize.

No database required. Just PHP, Composer, and an SMTP account.

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Features

• Single config file — edit config.php once, everything works
• Contact Us page — sends message to admin + auto-reply to visitor
• Subscribe page — welcome email to subscriber + admin notification
• Input sanitization — XSS-safe, validated before sending
• Responsive design — works on desktop, tablet, and mobile
• Lightweight — no heavy JS frameworks, no glowing effects, fast loading
• Easy theming — change one CSS variable to rebrand
• Bootstrap Icons — consistent icon set via CDN

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Pages

File	URL	Description
index.php	/	Landing page & documentation
contact.php	/contact.php	Contact Us form
subscribe.php	/subscribe.php	Newsletter subscribe form
config.php	—	SMTP configuration (edit this)
style.css	—	Shared stylesheet

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Requirements

• PHP 7.4 or higher
• Composer
• An SMTP account (Gmail, Mailgun, Mailtrap, etc.)

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Installation

1. Clone the repository

git clone https://github.com/cdn-lib/smtp.git
cd smtp

2. Install dependencies

composer require phpmailer/phpmailer

3. Configure your SMTP credentials

Open config.php and fill in your details:

define('SMTP_HOST',      'smtp.gmail.com');
define('SMTP_PORT',      465);
define('SMTP_USERNAME',  'your-email@gmail.com');   // Your SMTP email
define('SMTP_PASSWORD',  'your-app-password');       // App password
define('SMTP_FROM_NAME', 'Your Company Name');
define('SMTP_ENCRYPTION','ssl');                     // 'ssl' or 'tls'

define('ADMIN_EMAIL',    'admin@yourcompany.com');   // Receives contact messages
define('SITE_NAME',      'Your Company');
define('SITE_URL',       'https://yourcompany.com');

Gmail users: Enable 2-Step Verification and generate an App Password. Do NOT use your regular account password.

4. Deploy

Upload all files to your web server. No database setup needed.

your-server/
├── vendor/              ← generated by Composer
├── config.php
├── contact.php
├── index.php
├── style.css
├── subscribe.php
└── composer.json

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Configuration Reference

Constant	Default	Description
SMTP_HOST	smtp.gmail.com	SMTP server hostname
SMTP_PORT	465	465 for SSL, 587 for TLS
SMTP_USERNAME	—	SMTP login email
SMTP_PASSWORD	—	App password
SMTP_FROM_NAME	—	Sender display name
SMTP_ENCRYPTION	ssl	ssl or tls
ADMIN_EMAIL	—	Inbox that receives contact messages
SITE_NAME	—	Used in email subjects and footers
SITE_URL	—	Your website URL

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Theming / Customization

All colors are defined as CSS variables at the top of style.css:

:root {
  --accent:       #4F46E5;   /* Change this to rebrand */
  --accent-hover: #4338CA;
  --bg:           #F3F4F6;
  --bg-card:      #FFFFFF;
  /* ... more tokens */
}

To switch to a dark theme, just override the root variables in a <style> block on the pages you need.

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Customizing Subscribe Interests

In subscribe.php, edit the $interest_options array:

$interest_options = [
    'news'     => ['label' => 'Latest News',   'desc' => 'Stay up to date'],
    'products' => ['label' => 'New Products',  'desc' => 'First to know'],
    // Add or remove entries as needed
];

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Security Notes

• All POST inputs are sanitized with htmlspecialchars() and filter_var()
• SMTP credentials are stored in config.php — make sure this file is not publicly accessible if using plain PHP hosting
• For production, consider moving config.php above the web root
• Never commit real credentials — use environment variables or .env files in production

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SMTP Providers

Provider	Host	Port	Encryption
Gmail	smtp.gmail.com	465	SSL
Outlook	smtp.office365.com	587	TLS
Mailgun	smtp.mailgun.org	587	TLS
Mailtrap (testing)	smtp.mailtrap.io	2525	TLS
SendGrid	smtp.sendgrid.net	587	TLS

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License

MIT License — free to use, modify, and distribute.

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Credits

• PHPMailer — email sending library
• Bootstrap Icons — icon set
• Google Fonts — Inter — typography