來自 gsmtp 的退回郵件 - 奇怪的郵件路徑

請考慮退回給原始發件人的郵件中的以下電子郵件標頭。多部分退回郵件還包含原始發件人和預期收件人之間的通信記錄（明文+ HTML），我將其剝離。

問題是：這條消息是如何在 gmail 中出現的？

很長一段時間我以為我對（E）SMTP很熟悉，現在似乎不是這樣了。假設這不是假退回，我只能猜測指定了不同的信封收件人（發件人已被黑客入侵？），或者收件人的 MTA 中涉及一些密件抄送映射或別名功能。

以下實體已替換為其各自的佔位符：

• %original sender%- 實際將退回郵件轉發給的人%intended-recipient%
• %intended recipient%- 擔心她的安全的人，因為 %original-sender% 向她轉發了這條退回郵件
• %totally unrelated%@gmail.com- 某人的電子郵件地址，%original-sender% 和 %intended-recipient% 都沒有與之通信。

來自：郵件遞送系統

$$ mailto:Mailer-Daemon@ $$

發送時間：2013 年 10 月 17 日星期四下午 1:22

收件人：%original sender%

主題：郵件投遞失敗：將郵件返回給發件人

此消息是由郵件傳遞軟體自動創建的。

您發送的郵件無法傳遞給一個或多個

收件人。這是一個永久性錯誤。以下地址失敗：

**%totally unrelated%** @gmail.com  
SMTP error from remote mail server after end of data:  
host gmail-smtp-in.l.google.com [2a00:1450:4001:c02::1b]:  
550-5.7.1 [ **%currently unreachable IPv6 address%** 16] Our system has detected  
550-5.7.1 that this message does not meet IPv6 sending guidelines regarding PTR  
550-5.7.1 records and authentication. Please review  
550-5.7.1 https://support.google.com/mail/?p=ipv6_authentication_error for more  
550 5.7.1 information. u47si3796594eel.284 - gsmtp  
 
 
------ This is a copy of the message, including all the headers. ------  
 
Return-path: <**%original sender%**>  
 
Received:  
from **%MX of intended recipient%** ([ **%IP address of MX of intended recipient%** ])  
by **%another MTA in the network of recipient's ISP%** with esmtp (Exim 4.63 #1 (Debian))  
id 1VWleU-0006QW-Pl  
from < **%original sender%** >  
for < **%totally unrelated%** @gmail.com>; Thu, 17 Oct 2013 13:22:02 +0200  
 
Received:  
from **%MTA of sender's ISP%**([**%IP of MTA of sender's ISP%**])  
by **%MX of intended recipient%** with esmtp (Exim 4.69 #1 (Debian))  
id 1VWleU-0004oq-JG  
for <**%intended recipient%**>; Thu, 17 Oct 2013 13:22:02 +0200  

Received:  
from **%sender's hostname%** (**%sender's PTR%**[ **%sender's IP%** ])  
by **%MTA of sender's ISP%**(Postfix) with ESMTPA  
id 3d0nyG0hwJz1741X  
for <**%intended recipient%**>; Thu, 17 Oct 2013 13:21:41 +0200 (CEST)  
 
From: **%sender's name encoded%**  <**%original sender%**>  
To: **%intended recipient's name encoded%** <**%intended recipient%**>  
References: <000c01cecb17$d9321ef0$8b965cd0$@tlh>  
In-Reply-To: <000c01cecb17$d9321ef0$8b965cd0$@tlh>  
Subject: **%subject line encoded%**
Date: Thu, 17 Oct 2013 13:21:41 +0200  
Message-ID: <00b701cecb2b$0dfd9d40$29f8d7c0$@**%sender's domain%**>  
MIME-Version: 1.0  
Content-Type: multipart/alternative;  
       boundary="----=_NextPart_000_00B8_01CECB3B.D1866D40"  
X-Mailer: Microsoft Outlook 14.0  
Thread-Index: AQGITggPsq7UFiUmFwcnkdC2rH3HB5qFuXTQ  
Content-Language: tlh  
 
This is a multipart message in MIME format.  

最終使用者通過 MTA（如 /etc/aliases）轉發他們的電子郵件。

引用自：https://serverfault.com/questions/556906