{
  "id": "08-oversized-attachment",
  "category": "boundary",
  "from": "ops@example.com",
  "subject": "请查收新增预报 WHSU8127240",
  "text": "请查收新增预报，附件较大。",
  "messageId": "<08-oversized-attachment@fixtures.local>",
  "date": "2026-04-14T07:00:00.000Z",
  "attachments": [
    {
      "filename": "数据模版.xlsx",
      "kind": "oversized",
      "bytes": 20971521
    }
  ]
}