Only in nasmail-1.6.1/config: config.php
Only in nasmail-1.6.1/data: test.pref
diff -ur nasmail-1.6.1.orig/functions/mailbox_display.php nasmail-1.6.1/functions/mailbox_display.php
--- nasmail-1.6.1.orig/functions/mailbox_display.php	2008-05-26 19:21:56.000000000 +0300
+++ nasmail-1.6.1/functions/mailbox_display.php	2009-08-04 09:09:12.000000000 +0300
@@ -176,10 +176,10 @@
     }
 
     if (is_array($message_highlight_list) && count($message_highlight_list)) {
-        $msg['TO'] = parseAddress($msg['TO']);
-        $msg['CC'] = parseAddress($msg['CC']);
         foreach ($message_highlight_list as $message_highlight_list_part) {
-            if (trim($message_highlight_list_part['value']) != '') {
+            if (trim($message_highlight_list_part['value']) != '' && 
+                trim($message_highlight_list_part['color']) != '' && 
+                trim($message_highlight_list_part['match_type']) != '') {
                 $high_val   = strtolower($message_highlight_list_part['value']);
                 $match_type = strtoupper($message_highlight_list_part['match_type']);
                 if($match_type == 'TO_CC') {
@@ -192,12 +192,13 @@
                         case('TO'):
                         case('CC'):
                         case('FROM'):
-                            foreach ($msg[$match_type] as $address) {
+                            $aAddresses = parseAddress($msg[$match_type]);
+                            foreach ($aAddresses as $address) {
                                 $address[0] = decodeHeader($address[0], true, false);
                                 $address[1] = decodeHeader($address[1], true, false);
                                 if (strstr('^^' . strtolower($address[0]), $high_val) ||
                                     strstr('^^' . strtolower($address[1]), $high_val)) {
-                                    $hlt_color = $message_highlight_list_part['color'];
+                                    $hlt_color = '#' . $message_highlight_list_part['color'];
                                     break 4;
                                 }
                             }
@@ -205,7 +206,7 @@
                         default:
                             $headertest = strtolower(decodeHeader($msg[$match_type], true, false));
                             if (strstr('^^' . $headertest, $high_val)) {
-                                $hlt_color = $message_highlight_list_part['color'];
+                                $hlt_color = '#' . $message_highlight_list_part['color'];
                                 break 3;
                             }
                             break;
diff -ur nasmail-1.6.1.orig/src/options_highlight.php nasmail-1.6.1/src/options_highlight.php
--- nasmail-1.6.1.orig/src/options_highlight.php	2007-11-06 08:35:15.000000000 +0200
+++ nasmail-1.6.1/src/options_highlight.php	2009-08-04 09:13:02.000000000 +0300
@@ -58,6 +58,8 @@
     $message_highlight_list = array();
 }
 
+displayPageHeader($color, '');
+
 if (isset($theid) && ($action == 'delete') ||
                      ($action == 'up')     ||
                      ($action == 'down')) {
@@ -91,8 +93,6 @@
 
     setPref($data_dir, $username, 'hililist', serialize($message_highlight_list));
 
-    nsm_http_redirect('options_highlight.php');
-    exit;
 } else if ($action == 'save') {
 
     if ($color_type == 1) $newcolor = $newcolor_choose;
@@ -104,19 +104,24 @@
     $newcolor = str_replace('\'', '', $newcolor);
     $value = str_replace(',', ' ', $value);
 
-    if(isset($theid)) {
-        $message_highlight_list[$theid] =
-            array( 'name' => $identname, 'color' => $newcolor,
-                   'value' => $value, 'match_type' => $match_type );
-    } else {
-        $message_highlight_list[] =
-            array( 'name' => $identname, 'color' => $newcolor,
-                   'value' => $value, 'match_type' => $match_type );
-    }
+    if (! preg_match('/^[0-9a-f]{6}$|^[0-9a-f]{3}$/i',$newcolor)) { 
+        echo '<table cellspacing="0" cellpadding="0" border="0" width="100%" style="margin-bottom:5px"><tr><td>'; 
+        error_box(_("Invalid HTML color code"),$color); 
+        echo '</td></tr></table>'; 
+    } else { 
+        if(isset($theid)) {
+            $message_highlight_list[$theid] =
+                array( 'name' => $identname, 'color' => $newcolor,
+                       'value' => $value, 'match_type' => $match_type );
+        } else {
+            $message_highlight_list[] =
+                array( 'name' => $identname, 'color' => $newcolor,
+                       'value' => $value, 'match_type' => $match_type );
+        }
 
-    setPref($data_dir, $username, 'hililist', serialize($message_highlight_list));
+        setPref($data_dir, $username, 'hililist', serialize($message_highlight_list));
+    }
 }
-displayPageHeader($color, '');
 
 $title = _("Options") . ' - ' . _("Message Highlighting");
 echo nsm_page_title($title);