非常延遲的郵件傳遞。發生了什麼？

我有一個線上表格，可以將電子郵件發送到我的 gmail 帳戶。很長一段時間以來，它似乎一直正常工作，直到 2011 年 9 月 6 日突然有 250 多封電子郵件一次到達我的收件箱。但看看標題，這些是在 6 月和 8 月之間發送的。任何人都可以從標題中破譯發生了什麼？否則什麼機制可能導致這種情況？

Delivered-To: *******@gmail.com
Received: by 10.223.96.8 with SMTP id f8cs74668fan;
       Mon, 5 Sep 2011 23:27:50 -0700 (PDT)
Received: by 10.91.110.8 with SMTP id n8mr3292513agm.37.1315290469625;
       Mon, 05 Sep 2011 23:27:49 -0700 (PDT)
Return-Path: <httpd@web7.dh.com.sg>
Received: from web7.dh.com.sg ([203.117.141.130])
       by mx.google.com with ESMTPS id n15si3643530anb.191.2011.09.05.23.27.47
       (version=TLSv1/SSLv3 cipher=OTHER);
       Mon, 05 Sep 2011 23:27:48 -0700 (PDT)
Received-SPF: neutral (google.com: 203.117.141.130 is neither permitted nor denied by best guess record for domain of httpd@web7.dh.com.sg) client-ip=203.117.141.130;
Authentication-Results: mx.google.com; spf=neutral (google.com: 203.117.141.130 is neither permitted nor denied by best guess record for domain of httpd@web7.dh.com.sg) smtp.mail=httpd@web7.dh.com.sg
Received: from web7.dh.com.sg (localhost [127.0.0.1])
   by web7.dh.com.sg (8.13.1/8.13.1) with ESMTP id p866RV6P031284
   for &lt;*******@gmail.com&gt;; Tue, 6 Sep 2011 14:27:45 +0800
Received: (from httpd@localhost)
   by web7.dh.com.sg (8.13.1/8.13.1/Submit) id p5U9UX4N030130;
   Thu, 30 Jun 2011 17:30:33 +0800
Date: Thu, 30 Jun 2011 17:30:33 +0800
Message-Id: &lt;201106300930.p5U9UX4N030130@web7.dh.com.sg&gt;

Received: (from httpd@localhost)
   by web7.dh.com.sg (8.13.1/8.13.1/Submit) id p5U9UX4N030130;
   Thu, 30 Jun 2011 17:30:33 +0800

是罪魁禍首。它在六月收到了郵件，沒有轉發。不管什麼原因。然後在 9 月 6 日，它將延遲的郵件發送到

Received: from web7.dh.com.sg (localhost [127.0.0.1])
   by web7.dh.com.sg (8.13.1/8.13.1) with ESMTP id p866RV6P031284
   for <*******@gmail.com>; Tue, 6 Sep 2011 14:27:45 +0800

因此，要麼第一個無法傳遞，要麼第二個無法接收。有很多原因，所以這可能會發生。

1. 網路錯誤
2. 第二個超出儲存/配額
3. 第一個 SMTP 服務失敗
4. 第二次 SMTP 服務已關閉
5. 軟體故障
6. …

引用自：https://serverfault.com/questions/309788