What potential vulnerabilities exist in PHP forms that allow spambots to submit data?

One potential vulnerability in PHP forms that allow spambots to submit data is the lack of form validation. Spambots can easily bypass forms that do not have proper validation checks in place, allowing them to submit unwanted data. To solve this issue, implement server-side form validation to ensure that only legitimate data is accepted.

// Server-side form validation
if ($_SERVER["REQUEST_METHOD"] == "POST") {
    if (empty($_POST["name"]) || empty($_POST["email"]) || empty($_POST["message"])) {
        echo "Please fill out all required fields.";
    } else {
        // Process form data
    }
}