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自建 Mail System 的難度

Hacker News 上的「Ask HN: Is it possible to run your own mail server for personal use?」這篇道出了現在自建 mail system 的難度。作者遇到信件常常被各大 mail 服務歸類成 spam:

The problem is making sure my mail is not marked as spam by the major MTAs out there, gmail and hotmail both mark my mails as spam.

整理一下現在自己建 mail system 要做到哪些事情:

  • 確認 IP (包括 IPv4/IPv6) 沒有列入任何 Open Relay 清單中。
  • 確認 IP 的反解可以查出對應的正解。
  • 確認 SPF 設定。
  • 確認送出去的信件有 DKIM 簽名,而且 DNS 也有設上對應的設定。
  • 確認 TLS 的發送與接收都正常。
  • 確認 DMARC 機制正確運作。

如同「Exercising Software Freedom in the Global Email System」這邊講的,現在要自己搞 mail system 超累...

結合 Malware 與 Social Engineering 的詐騙

在「Malware scam appears to use GPS data to catch speeding Pennsylvania drivers」這邊看到新的詐騙方式。

手機的 malware app (藏有惡意程式的 app) 會要求 GPS 資料 (現在智慧型手機上 app 的常態),而當 malware app 偵測到你超速時,詐騙集團就會發出假的超速罰單,像是這樣:

From: Speeding Citation
To: (Accurate Email Removed)
Date: 03/11/2016 03:08 PM
Subject: [External] Notification of excess speed
First Name: (Accurate Name removed)
Last Name: (Accurate Name removed)
Notification of excess speed
Route: (Accurate Local Township Road –removed)
Date: 8 March 2016
Time: 7:55 am
Speed Limit: 40
Detected Speed: 52
The Infraction Statement contains an image of your license plate and the citation which must be paid in 5 working days.

文章提用的標語「ACCURATE SPEEDING DATA, FAKE EMAIL」好讚... XD

StartSSL 的認證出包

這幾天還蠻歡樂的新聞,StartSSL 的認證過程出包,可以用任何 email 收認證信:「StartSSL Domain validation (Vulnerability discovered).」。直接看這張圖就好:

這樣傳不是問題 (因為你還是可以在 server 端再確認一次),而是改了會動 (樂):

這家公司最近傳出好多負面新聞... (啊,我把他們家的 root certificate 標成 untrusted 一陣子了 XD)

MediaWiki 的 EmailDiff 套件

先前 MediaWiki 所提供的「變更通知」都只有在信件裡「通知」,而沒有在信件裡列出「改變的內容」,這使得讀信的人要再點進去看... (於是就懶的點了)

而前陣子看到有人寫了 extension 來輸出 diff,解決了這個問題:「MediaWiki extension EmailDiff: notification emails improved」。

信裡變成有這樣的內容:

Version differences:
@@ -846,5 +887,3 @@
 In cattle, temperament can affect production traits such as carcass and meat 
 quality or milk yield as well as affecting the animal's overall health and 
-reproduction. Cattle temperament is defined as "the consistent behavioral and physiological 
-difference observed between individuals in response to a stressor or environmental 
+reproduction. If you succeed in tipping a cow only partway, such that only one 
+of its feet is still on the ground, you have created lean beef. Such a feat is 
+well done. Naturally, being outside, the cow is unstable. When it falls over, 
+it becomes ground beef. Cattle temperament is defined as "the consistent behavioral 
+and physiological difference observed between individuals in response to a stressor or environmental 
 challenge and is used to describe the relatively stable difference in the behavioral 
 predisposition of an animal, which can be related to psychobiological mechanisms.

這樣可讀性高非常多,來找人裝看看好了...

追蹤開信的能力

追蹤開信的能力是廣告信經常會用到的能力,為了要看「成效」而要追蹤開信率之類的數字。

在「Email Privacy Tester」這邊看到有趣的工具,介紹了「Email Privacy Tester」這個網站可以拿來測試各種 mail client 上可被追蹤的功能。

依照作者測試,Gmail 完美的擋下目前所有追蹤技巧:

Apple Mail 還很慘,有一堆方式可以被追蹤開信:

不知道其他家 (像是 Yahoo) 的情況...

Gmail 將會提示沒有支援 STARTTLS 的信箱

Gmail 界面將會提示不支援 STARTTLS 的信箱:「Making email safer for you」。

先確認 msa.hinet.net 的 MX record:

;; ANSWER SECTION:
msa.hinet.net.          86174   IN      MX      0 msa-smtp-mx1.hinet.net.
msa.hinet.net.          86174   IN      MX      0 msa-smtp-mx2.hinet.net.

以及不支援 STARTTLS (在 EHLO 後不會出現 STARTTLS 選項):

$ t msa-smtp-mx1.hinet.net 25
Trying 168.95.6.53...
Connected to msa-smtp-mx1.hinet.net.
Escape character is '^]'.
220 msa.hinet.net ESMTP Sendmail 8.14.2/8.14.2; Thu, 11 Feb 2016 04:52:16 +0800 (CST)
EHLO localhost
250-msa.hinet.net Hello 114-32-152-63.HINET-IP.hinet.net [114.32.152.63], pleased to meet you
250-ENHANCEDSTATUSCODES
250-PIPELINING
250-8BITMIME
250-SIZE
250-DSN
250-ETRN
250-DELIVERBY
250 HELP
QUIT
221 2.0.0 msa.hinet.net closing connection
Connection closed by foreign host.

打開 Gmail 在收件人的地方輸入 test@msa.hinet.net 後,就會跳出紅色鎖頭表示不支援 STARTTLS。

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