--- dokuwiki-20110329/inc/common.php~	2011-03-29 09:15:04.000000000 +0300
+++ dokuwiki-20110329/inc/common.php	2011-03-29 09:16:58.468168676 +0300
@@ -1190,7 +1190,21 @@
     }else{
         $subject = '['.$conf['mailprefix'].'] '.$subject;
     }
-    mail_send($to,$subject,$text,$conf['mailfrom'],'',$bcc);
+
+    $headers = array();
+    // add mail headers to identify page changes in same mail thread
+    $file = wikiFN($id);
+    $cur = @filemtime($file);
+    $headers['Message-Id'] = "$id?rev=$cur";
+    if ($rev) {
+        $headers['In-Reply-To'] = "$id?rev=$rev";
+    }
+    $h = '';
+    foreach ($headers as $k => $v) {
+        $h .= sprintf("%s: %s%s", $k, $v, MAILHEADER_EOL);
+    }
+
+    mail_send($to,$subject,$text,$conf['mailfrom'],'',$bcc,$h);
 }
 
 /**