diff --git a/plugins/calendar/calendar.php b/plugins/calendar/calendar.php
index 4975f7c2..36947ea1 100644
--- a/plugins/calendar/calendar.php
+++ b/plugins/calendar/calendar.php
@@ -1800,13 +1800,14 @@ class calendar extends rcube_plugin
       
       // which template to use for mail text
       $is_new = !in_array($attendee['email'], $old_attendees);
+      $is_rsvp = $is_new || $event['sequence'] > $old['sequence'];
       $bodytext = $is_cancelled ? 'eventcancelmailbody' : ($is_new ? 'invitationmailbody' : 'eventupdatemailbody');
       $subject  = $is_cancelled ? 'eventcancelsubject'  : ($is_new ? 'invitationsubject' : ($event['title'] ? 'eventupdatesubject':'eventupdatesubjectempty'));
 
       $event['comment'] = $comment;
 
       // finally send the message
-      if ($itip->send_itip_message($event, $method, $attendee, $subject, $bodytext, $message))
+      if ($itip->send_itip_message($event, $method, $attendee, $subject, $bodytext, $message, $is_rsvp))
         $sent++;
       else
         $sent = -100;
diff --git a/plugins/libcalendaring/lib/libcalendaring_itip.php b/plugins/libcalendaring/lib/libcalendaring_itip.php
index 0b21ed8c..6ff1229d 100644
--- a/plugins/libcalendaring/lib/libcalendaring_itip.php
+++ b/plugins/libcalendaring/lib/libcalendaring_itip.php
@@ -92,7 +92,7 @@ class libcalendaring_itip
      * @param object  Mail_mime object with message data
      * @return boolean True on success, false on failure
      */
-    public function send_itip_message($event, $method, $recipient, $subject, $bodytext, $message = null)
+    public function send_itip_message($event, $method, $recipient, $subject, $bodytext, $message = null, $rsvp = true)
     {
         if (!$this->sender['name'])
             $this->sender['name'] = $this->sender['email'];
@@ -125,7 +125,7 @@ class libcalendaring_itip
             'vars' => array(
                 'title' => $event['title'],
                 'date' => $this->lib->event_date_text($event, true),
-                'attendees' => join(', ', $attendees_list),
+                'attendees' => join(",\n ", $attendees_list),
                 'sender' => $this->sender['name'],
                 'organizer' => $this->sender['name'],
             )
@@ -136,7 +136,7 @@ class libcalendaring_itip
         // }
 
         // append links for direct invitation replies
-        if ($method == 'REQUEST' && ($token = $this->store_invitation($event, $recipient['email']))) {
+        if ($method == 'REQUEST' && $rsvp && ($token = $this->store_invitation($event, $recipient['email']))) {
             $mailbody .= "\n\n" . $this->gettext(array(
                 'name' => 'invitationattendlinks',
                 'vars' => array('url' => $this->plugin->get_url(array('action' => 'attend', 't' => $token))),
diff --git a/plugins/tasklist/tasklist.php b/plugins/tasklist/tasklist.php
index c943f54c..4004a9ba 100644
--- a/plugins/tasklist/tasklist.php
+++ b/plugins/tasklist/tasklist.php
@@ -734,11 +734,12 @@ class tasklist extends rcube_plugin
 
             // which template to use for mail text
             $is_new   = !in_array($attendee['email'], $old_attendees);
+            $is_rsvp  = $is_new || $task['sequence'] > $old['sequence'];
             $bodytext = $is_cancelled ? 'itipcancelmailbody' : ($is_new ? 'invitationmailbody' : 'itipupdatemailbody');
             $subject  = $is_cancelled ? 'itipcancelsubject'  : ($is_new ? 'invitationsubject' : ($task['title'] ? 'itipupdatesubject' : 'itipupdatesubjectempty'));
 
             // finally send the message
-            if ($itip->send_itip_message($object, $method, $attendee, $subject, $bodytext, $message))
+            if ($itip->send_itip_message($object, $method, $attendee, $subject, $bodytext, $message, $is_rsvp))
                 $sent++;
             else
                 $sent = -100;