Index: kernel/classes/ezcollaborationitemhandler.php
===================================================================
--- kernel/classes/ezcollaborationitemhandler.php	(revision 19875)
+++ kernel/classes/ezcollaborationitemhandler.php	(working copy)
@@ -192,6 +192,8 @@
                 $parameters['reply_to'] = $tpl->variable( 'reply_to' );
             if ( $tpl->hasVariable( 'from' ) )
                 $parameters['from'] = $tpl->variable( 'from' );
+            if ( $tpl->hasVariable( 'content_type' ) )
+                $parameters['content_type'] = $tpl->variable( 'content_type' );
 
             $collection = eZNotificationCollection::create( $event->attribute( 'id' ),
                                                             EZ_COLLABORATION_NOTIFICATION_HANDLER_ID,
@@ -245,6 +247,8 @@
                     $parameters['reply_to'] = $tpl->variable( 'reply_to' );
                 if ( $tpl->hasVariable( 'from' ) )
                     $parameters['from'] = $tpl->variable( 'from' );
+                if ( $tpl->hasVariable( 'content_type' ) )
+                    $parameters['content_type'] = $tpl->variable( 'content_type' );
 
                 $collection = eZNotificationCollection::create( $event->attribute( 'id' ),
                                                                 EZ_COLLABORATION_NOTIFICATION_HANDLER_ID,
Index: kernel/classes/notification/ezmailnotificationtransport.php
===================================================================
--- kernel/classes/notification/ezmailnotificationtransport.php	(revision 19875)
+++ kernel/classes/notification/ezmailnotificationtransport.php	(working copy)
@@ -85,6 +85,8 @@
             $mail->addExtraHeader( 'In-Reply-To', $parameters['reply_to'] );
         if ( isset( $parameters['from'] ) )
             $mail->setSenderText( $parameters['from'] );
+        if ( isset( $parameters['content_type'] ) )
+            $mail->setContentType( $parameters['content_type'] );
         $mailResult = eZMailTransport::send( $mail );
         return $mailResult;
     }
Index: kernel/classes/notification/handler/ezsubtree/ezsubtreehandler.php
===================================================================
--- kernel/classes/notification/handler/ezsubtree/ezsubtreehandler.php	(revision 19875)
+++ kernel/classes/notification/handler/ezsubtree/ezsubtreehandler.php	(working copy)
@@ -161,6 +161,8 @@
             $parameters['reply_to'] = $tpl->variable( 'reply_to' );
         if ( $tpl->hasVariable( 'from' ) )
             $parameters['from'] = $tpl->variable( 'from' );
+        if ( $tpl->hasVariable( 'content_type' ) )
+            $parameters['content_type'] = $tpl->variable( 'content_type' );
 
         $collection = eZNotificationCollection::create( $event->attribute( 'id' ),
                                                         EZ_SUBTREE_NOTIFICATION_HANDLER_ID,