From mark at msapiro.net  Thu Jul  1 00:18:53 2021
From: mark at msapiro.net (Mark Sapiro)
Date: Wed, 30 Jun 2021 17:18:53 -0700
Subject: Ban .html as attachment but not html mails?
In-Reply-To: <15a5f628-7a47-573a-fc8a-fa4933248aa@barendse.to>
References: <15a5f628-7a47-573a-fc8a-fa4933248aa@barendse.to>
Message-ID: <58ad9c44-173a-9508-983b-b718487631e7@msapiro.net>

On 6/30/21 12:30 PM, Remco Barendse wrote:
> MOre and more malicious emails are coming in with .html as an attachment.
> 
> I do not need my users to receive .html files, ever
> 
> Blocking them in /etc/MailScanner/filename.rules.conf
> #deny?? \.htm$????????? Dangerous attachment type #deny   
> \.html$???????? Dangerous attachment type
> 
> Blocks every email in html, not exactly what I wanted.
> 
> What is the proper way to do it?


Consider that most MUAs that compose "rich text" email will create a 
message with the following MIME structure

multipart/alternative
     text/plain
         a plain text rendition of the message
     text/html
         a rich text rendition of the message

Compare that to the structure of a message with a plain text body and an 
HTML attachment.

multipart/mixed
     text/plain
         the plain text message
     text/html
         an HTML attachment

MailScanner currently does not distinguish between these two cases.

-- 
Mark Sapiro <mark at msapiro.net>        The highway is for gamblers,
San Francisco Bay Area, California    better use your sense - B. Dylan

From jmgorro at gmail.com  Tue Jul  6 05:10:51 2021
From: jmgorro at gmail.com (Josep M Gorro)
Date: Tue, 6 Jul 2021 07:10:51 +0200
Subject: TLS on MailScanner
Message-ID: <CAFOCrcVDeJPxXBiGRQJr7RN__Yc_Dc_5dYOzxH1Wn-bMu9WELw@mail.gmail.com>

Hello all.
I have a MailScanner server analyzing all SMTP between internal MTA (with
certificate) and the world.
I would like to be sure if I need to implement TLS 1.2 in some way on it or
is just required between on-premises MTA and the receiver MTA.

Thanks.

-- 

http://www.linkedin.com/in/jmgorro
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