$params['header_id']['api.default'] = CRM_Mailing_PseudoConstant::defaultComponent('Header', '');
$params['footer_id']['api.default'] = CRM_Mailing_PseudoConstant::defaultComponent('Footer', '');
$params['header_id']['api.default'] = CRM_Mailing_PseudoConstant::defaultComponent('Header', '');
$params['footer_id']['api.default'] = CRM_Mailing_PseudoConstant::defaultComponent('Footer', '');