Are there any potential security risks to consider when sending emails with PHP?

One potential security risk when sending emails with PHP is the possibility of email injection attacks, where malicious users can inject additional headers into the email to manipulate the email content or send spam. To prevent this, always sanitize user input and use the `mb_encode_mimeheader()` function to properly encode email headers. 

// Sanitize user input for email headers
$subject = filter_var($_POST['subject'], FILTER_SANITIZE_STRING);
$message = filter_var($_POST['message'], FILTER_SANITIZE_STRING);
$to = filter_var($_POST['to'], FILTER_SANITIZE_EMAIL);

// Encode email headers to prevent email injection attacks
$subject = mb_encode_mimeheader($subject, 'UTF-8', 'Q');
$headers = "From: sender@example.com\r\n";
$headers .= "MIME-Version: 1.0\r\n";
$headers .= "Content-Type: text/html; charset=UTF-8\r\n";

// Send email
mail($to, $subject, $message, $headers);

Keywords

PHP email security risks SMTP validation

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