function mail_task_handler()
    {
        // make sure we're not in ajax request
        if ($this->rc->output->type != 'html') {
            return;
        }

        // use jQuery for popup window
        $this->require_plugin('jqueryui');

        // include js script and localization
        $this->init_ui();

        // add 'Create filter' item to message menu
        $this->api->add_content(html::tag('li', null, 
            $this->api->output->button(array(
                'command'  => 'managesieve-create',
                'label'    => 'managesieve.filtercreate',
                'type'     => 'link',
                'classact' => 'icon filterlink active',
                'class'    => 'icon filterlink',
                'innerclass' => 'icon filterlink',
            ))), 'messagemenu');

        // register some labels/messages
        $this->rc->output->add_label('managesieve.newfilter', 'managesieve.usedata',
            'managesieve.nodata', 'managesieve.nextstep', 'save');

        $this->rc->session->remove('managesieve_current');
    }