--- user.module	2006-08-07 09:29:40.000000000 +0100
+++ user.module.new1	2006-08-14 15:36:56.000000000 +0100
@@ -341,6 +341,31 @@
  * Send an e-mail message.
  */
 function user_mail($mail, $subject, $message, $header) {
+  $defaults = array(
+    'MIME-Version' => '1.0',
+    'Content-Type' => 'text/plain; charset=UTF-8; format=flowed',
+    'Content-Transfer-Encoding' => '8Bit',
+    'X-Mailer' => 'Drupal'
+  );
+
+	// remove all '\r' and explode the header
+	$header = str_replace('\r', '', $header);
+	$headers = explode("\n", $header);
+	foreach($headers as $key) {
+		$dummy = explode(":", $key);
+		if (strtolower($dummy[0]) == 'reply-to') $dummy[0] = 'Reply-To';
+		if (strtolower($dummy[0]) == 'return-path') $dummy[0] = 'Return-Path';
+		if (strtolower($dummy[0]) == 'errors-to') $dummy[0] = 'Errors-To';
+		if ($dummy[0] != '' && !isset($defaults[$dummy[0]])) {
+			$defaults[$dummy[0]] = $dummy[1];
+		}
+	}
+
+  if (isset($defaults['From'])) {
+    $defaults['Reply-To'] = $defaults['Return-Path'] = $defaults['Errors-To'] = $defaults['From'];
+  }
+
+  // Allow for custom mail backend
   if (variable_get('smtp_library', '') && file_exists(variable_get('smtp_library', ''))) {
     include_once variable_get('smtp_library', '');
     return user_mail_wrapper($mail, $subject, $message, $header);
@@ -366,11 +391,15 @@
     ** http://www.rfc-editor.org/rfc/rfc2646.txt
     **
     */
+    $mimeheaders = array();
+    foreach ($headers as $name => $value) {
+      $mimeheaders[] = $name .': '. mime_header_encode($value);
+    }
     return mail(
-      $mail,
+      $to,
       mime_header_encode($subject),
-      str_replace("\r", '', $message),
-      "MIME-Version: 1.0\nContent-Type: text/plain; charset=UTF-8; format=flowed\nContent-transfer-encoding: 8Bit\n" . $header
+      str_replace("\r", '', $body),
+      join("\n", $mimeheaders)
     );
   }
 }