diff --git a/lib/weblib.php b/lib/weblib.php
index 1232659a261..d314ef249a1 100644
--- a/lib/weblib.php
+++ b/lib/weblib.php
@@ -1528,7 +1528,7 @@ function purify_html($text, $options = array()) {
         $config->set('Core.ConvertDocumentToFragment', true);
         $config->set('Core.Encoding', 'UTF-8');
         $config->set('HTML.Doctype', 'XHTML 1.0 Transitional');
-        $config->set('URI.AllowedSchemes', array('http'=>true, 'https'=>true, 'ftp'=>true, 'irc'=>true, 'nntp'=>true, 'news'=>true, 'rtsp'=>true, 'teamspeak'=>true, 'gopher'=>true, 'mms'=>true));
+        $config->set('URI.AllowedSchemes', array('http'=>true, 'https'=>true, 'ftp'=>true, 'irc'=>true, 'nntp'=>true, 'news'=>true, 'rtsp'=>true, 'teamspeak'=>true, 'gopher'=>true, 'mms'=>true, 'mailto'=>true));
         $config->set('Attr.AllowedFrameTargets', array('_blank'));
 
         if (!empty($CFG->allowobjectembed)) {