Are there any best practices for implementing spam filters in PHP to prevent unwanted content in contact forms?

Spam filters can help prevent unwanted content in contact forms by implementing techniques such as CAPTCHA challenges, honeypot fields, and blacklisting known spam domains or keywords. These filters can help reduce the amount of spam submissions received through contact forms and improve the overall user experience. 

// Example PHP code snippet for implementing a CAPTCHA challenge in a contact form

session_start();

// Generate a random CAPTCHA code
$captcha_code = substr(md5(rand()), 0, 6);
$_SESSION['captcha_code'] = $captcha_code;

// Display the CAPTCHA image in the form
echo '<img src="captcha_image.php" alt="CAPTCHA Image">';

// Validate the CAPTCHA code on form submission
if(isset($_POST['submit'])){
    if($_POST['captcha_input'] == $_SESSION['captcha_code']){
        // CAPTCHA code is correct, process the form submission
    } else {
        // CAPTCHA code is incorrect, display an error message
        echo 'Invalid CAPTCHA code, please try again.';
    }
}

Keywords

spam filters PHP contact forms unwanted content implementation

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