邮件头解析
原始邮件头折叠行展開與键值展示。全程瀏覽器本地處理，不上傳服務器。
| From | sender@example.com |
| To | you@example.com |
| Subject | =?UTF-8?B?5rWL6K+V?= test |
| Date | Mon, 1 Jan 2024 12:00:00 +0000 |
| Message-ID | <abc@mail.example.com> |
| Received | from mx1.example.com by inbox; Mon, 1 Jan 2024 12:01:00 +0000 |