diff --git a/forward.module b/forward.module
index 48ef1ab..a4c0564 100644
--- a/forward.module
+++ b/forward.module
@@ -214,6 +214,12 @@ function forward_admin_settings($form, &$form_state) {
     '#maxlength' => 40,
     '#description' => t('If left blank, the from address entered in the form will be used as the from address for the email.  Enter a valid email address here to override that.  The sender\'s email will still appear in the body of the message.'),
   );
+  $form['forward_options']['forward_sender_ip_address'] = array(
+    '#type' => 'checkbox',
+    '#title' => t('Add user\'s IP address to the email header'),
+    '#default_value' => variable_get('forward_sender_ip_address', TRUE),
+    '#description' => t('This allows the recipient to see the IP address of the sender, e.g. to trace the origin of spam. Do not check this if you do not want to reveal the sender\'s IP address to the recipient.'),
+  );
 
   $types = node_type_get_types();
   $options = array();
@@ -1079,6 +1085,9 @@ function forward_mail($key, &$message, $params) {
     $message['headers']['MIME-Version'] = '1.0';
     $message['headers']['Content-Type'] = 'text/html; charset=utf-8';
     $message['headers']['Reply-To'] = $params['headers']['Reply-To'];
+    if (variable_get('forward_sender_ip_address', TRUE)) {
+      $message['headers']['X-Originating-IP'] = '[' . ip_address() . ']';
+    }
   }
 }