Index: includes/mail.inc
===================================================================
RCS file: /cvs/drupal/drupal/includes/mail.inc,v
retrieving revision 1.8
diff -u -p -r1.8 mail.inc
--- includes/mail.inc	25 Jan 2008 17:04:00 -0000	1.8
+++ includes/mail.inc	7 Feb 2008 17:16:04 -0000
@@ -82,6 +82,10 @@
  */
 function drupal_mail($module, $key, $to, $language, $params = array(), $from = NULL, $send = TRUE) {
   $default_from = variable_get('site_mail', ini_get('sendmail_from'));
+  // The ini variable may not conform to the addr-spec format site_mail has. A check is needed.
+  if (valid_email_address($default_from)) {
+    $default_from = '"'. variable_get('site_name', 'Drupal') .'" <'. $default_from .'>';
+  }
 
   // Bundle up the variables into a structured array for altering.
   $message = array(