What are the potential pitfalls of using register_globals in PHP form scripts for automatic email sending, and why should it be avoided?

Using register_globals in PHP form scripts can lead to security vulnerabilities such as injection attacks and data manipulation. It is recommended to avoid using register_globals as it can make your code more prone to security risks and make it harder to maintain and debug in the long run.

// Disable register_globals in PHP configuration
// This can be done by setting the following directive in php.ini file:
// register_globals = Off