查询指定邮件组

{
    "code": 0,
    "msg": "success",
    "data": {
        "mailgroup_id": "xxxxxxxxxxxxxxx",
        "email": "test_mail_group@xxx.xx",
        "name": "test mail group",
        "description": "mail group for testing",
        "direct_members_count": "10",
        "include_external_member": true,
        "include_all_company_member": false,
        "who_can_send_mail": "ALL_INTERNAL_USERS"
    }
}