Are there any security concerns to consider when selecting recipients in a PHP mail script?

When selecting recipients in a PHP mail script, it is important to sanitize and validate user input to prevent malicious code injection or email header injection attacks. This can be done by using PHP's filter_var() function with the FILTER_VALIDATE_EMAIL filter to ensure that the email addresses provided are valid. 

// Sanitize and validate recipient email addresses
$recipients = $_POST['recipients'];
$recipients_array = explode(',', $recipients);

foreach ($recipients_array as $recipient) {
    $recipient = trim($recipient);
    if (filter_var($recipient, FILTER_VALIDATE_EMAIL)) {
        // Send email to valid recipient
        mail($recipient, $subject, $message);
    } else {
        // Handle invalid email address
        echo "Invalid email address: $recipient";
    }
}

Keywords

PHP mail script security concerns recipient selection email validation injection attacks

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