diff -ruNa rc-beta2/program/localization/en_US/messages.inc rc-beta/program/localization/en_US/messages.inc
--- rc-beta2/program/localization/en_US/messages.inc	2008-12-20 09:56:23.000000000 +0100
+++ rc-beta/program/localization/en_US/messages.inc	2008-12-24 11:22:06.863847460 +0100
@@ -40,6 +40,8 @@
 $messages['nocontactsfound'] = 'No contacts found';
 $messages['contactnotfound'] = 'The requested contact was not found';
 $messages['sendingfailed'] = 'Failed to send message';
+$messages['sendingerror'] = 'Failed to send message!<br />$error';
+$messages['sendingreceipterror'] = 'Failed to send receipt!<br />$error';
 $messages['senttooquickly'] = 'Please wait $sec sec(s). before sending this message';
 $messages['errorsavingsent'] = 'An error occured while saving sent message';
 $messages['errorsaving'] = 'An error occured while saving';
diff -ruNa rc-beta2/program/localization/pl_PL/messages.inc rc-beta/program/localization/pl_PL/messages.inc
--- rc-beta2/program/localization/pl_PL/messages.inc	2008-12-20 09:56:21.000000000 +0100
+++ rc-beta/program/localization/pl_PL/messages.inc	2008-12-24 11:20:50.110172849 +0100
@@ -45,6 +45,8 @@
 $messages['nocontactsfound'] = 'Nie znaleziono kontaktu!';
 $messages['contactnotfound'] = 'Szukany kontakt nie został odnaleziony';
 $messages['sendingfailed'] = 'Nie udało się wysłać wiadomości!';
+$messages['sendingerror'] = 'Nie udało się wysłać wiadomości!<br />$error';
+$messages['sendingreceipterror'] = 'Nie można wysłać potwierdzenia!<br />$error';
 $messages['senttooquickly'] = 'Musisz poczekać $sec sek. aby móc wysłać tą wiadomość!';
 $messages['errorsavingsent'] = 'Wystąpił błąd podczas zapisu wysłanej wiadomości!';
 $messages['errorsaving'] = 'Wystąpił błąd podczas zapisu!';
diff -ruNa rc-beta2/program/steps/mail/func.inc rc-beta/program/steps/mail/func.inc
--- rc-beta2/program/steps/mail/func.inc	2008-12-20 09:56:25.000000000 +0100
+++ rc-beta/program/steps/mail/func.inc	2008-12-25 09:01:33.792098656 +0100
@@ -1213,7 +1213,7 @@
 /**
  * Send the given message compose object using the configured method
  */
-function rcmail_deliver_message(&$message, $from, $mailto)
+function rcmail_deliver_message(&$message, $from, $mailto, &$smtp_response)
 {
   global $CONFIG, $RCMAIL;
 
@@ -1285,7 +1285,7 @@
 }
 
 
-function rcmail_send_mdn($uid)
+function rcmail_send_mdn($uid, &$response)
 {
   global $RCMAIL, $IMAP;
 
@@ -1342,7 +1342,7 @@
     $compose->setTXTBody(wordwrap($body, 75, "\r\n"));
     $compose->addAttachment($report, 'message/disposition-notification', 'MDNPart2.txt', false, '7bit', 'inline');
 
-    $sent = rcmail_deliver_message($compose, $identity['email'], $mailto);
+    $sent = rcmail_deliver_message($compose, $identity['email'], $mailto, $response);
 
     if ($sent)
     {
diff -ruNa rc-beta2/program/steps/mail/sendmail.inc rc-beta/program/steps/mail/sendmail.inc
--- rc-beta2/program/steps/mail/sendmail.inc	2008-12-20 09:56:24.000000000 +0100
+++ rc-beta/program/steps/mail/sendmail.inc	2008-12-25 09:00:43.126960661 +0100
@@ -363,12 +363,15 @@
     $OUTPUT->send('iframe'); 
   }
 
-  $sent = rcmail_deliver_message($MAIL_MIME, $from, $mailto);
+  $sent = rcmail_deliver_message($MAIL_MIME, $from, $mailto, $response);
   
   // return to compose page if sending failed
   if (!$sent)
     {
-    $OUTPUT->show_message("sendingfailed", 'error'); 
+    if ($response)
+      $OUTPUT->show_message('sendingerror', 'error', array('error' => join("\n", $response))); 
+    else
+      $OUTPUT->show_message('sendingfailed', 'error'); 
     $OUTPUT->send('iframe');
     }
 
diff -ruNa rc-beta2/program/steps/mail/sendmdn.inc rc-beta/program/steps/mail/sendmdn.inc
--- rc-beta2/program/steps/mail/sendmdn.inc	2008-12-20 09:56:24.000000000 +0100
+++ rc-beta/program/steps/mail/sendmdn.inc	2008-12-24 11:07:02.716336103 +0100
@@ -21,7 +21,7 @@
 
 
 if (!empty($_POST['_uid'])) {
-  $sent = rcmail_send_mdn(get_input_value('_uid', RCUBE_INPUT_POST));
+  $sent = rcmail_send_mdn(get_input_value('_uid', RCUBE_INPUT_POST), $response);
 }
 
 // show either confirm or error message
@@ -29,6 +29,9 @@
   $OUTPUT->set_env('mdn_request', false);
   $OUTPUT->show_message('receiptsent', 'confirmation');
 }
+else if ($response) {
+  $OUTPUT->show_message('sendingreceipterror', 'error', array('error' => join("\n", $response)));
+}
 else {
   $OUTPUT->show_message('errorsendingreceipt', 'error');
 }