Index: includes/mail.inc
===================================================================
--- includes/mail.inc
+++ includes/mail.inc
@@ -82,7 +82,13 @@
  */
 function drupal_mail($module, $key, $to, $language, $params = array(), $from = NULL, $send = TRUE) {
   $default_from = variable_get('site_mail', ini_get('sendmail_from'));
-
+  // Use 'site name' in the 'From' header.
+  // According to the documentation of RCF 2822 it is necessary to encode 
+  // string that contain non-ASCII characters.
+  if (valid_email_address($default_from)) {
+    $site_name    = variable_get('site_name', 'Drupal');
+    $default_from = mime_header_encode($site_name).' <'. $default_from .'>';
+  }
   // Bundle up the variables into a structured array for altering.
   $message = array(
     'id'       => $module .'_'. $key,