neoroles/Email-Spoofing-PHP ? reverse-engineered prompt

Build me a small PHP demo project that shows how email spoofing works for security research and education, but keep it clearly safe and harmless. I want a few simple examples that send test emails with a custom From name, Reply To, and HTML message using PHP mail, plus one example using SMTP with PHPMailer so I can compare the two approaches. Please make it easy to run locally, with a couple of sample scripts and a README that explains what each example does and warns that it should only be used in a controlled test environment. If you can, include a clean sample page or script that lets me fill in recipient, sender name, subject, and message, then sends a test email and shows success or failure. Use current docs online if you need to.