创建邮件组 POST {{base_url}}/mail/v1/mailgroups 创建一个邮件组 参考接口文档：创建邮件组 Request Body {"description"=>"mail group for testing", "email"=>"test_mail_group@xxx.xx", "name"=>"test mail group", "who_can_send_mail"=>"ALL_INTERNAL_USERS"}