What are some common pitfalls for beginners when using PHP for form mailers?

One common pitfall for beginners when using PHP for form mailers is not properly sanitizing user input, which can lead to security vulnerabilities such as SQL injection or cross-site scripting attacks. To solve this issue, always use PHP's built-in functions like htmlspecialchars() or mysqli_real_escape_string() to sanitize user input before using it in SQL queries or displaying it on the webpage.

// Sanitize user input before using it in SQL queries
$name = mysqli_real_escape_string($conn, $_POST['name']);
$email = mysqli_real_escape_string($conn, $_POST['email']);
$message = mysqli_real_escape_string($conn, $_POST['message']);

// Sanitize user input before displaying it on the webpage
$name = htmlspecialchars($_POST['name']);
$email = htmlspecialchars($_POST['email']);
$message = htmlspecialchars($_POST['message']);