protected function _prepareLayout()
    {
        $this->buttonList->remove('save');
        $this->buttonList->remove('delete');
        $this->buttonList->remove('reset');

        $this->buttonList->add(
            'send',
            [
                'label' => __('Send mail ...'),
                'onclick' => "setLocation('{$this->getUrl('*/*/send', 
                    ['id' => $this->_mail->getId()]
                    )}')",
                'class' => 'task'
            ]
        );

        $this->buttonList->add(
            'send_post',
            [
                'label' => __('Resend mail'),
                'onclick' => "setLocation('{$this->getUrl('*/*/sendPost', 
                [
                    'id' => $this->_mail->getId()
                ])}')",
                'class' => 'task'
            ]
        );

        return parent::_prepareLayout();
    }