I can see the plain text version, but when I try to view the HTML version I get this message:
This is a bug in Mailwasher, as I will explain below. Would it be possible for Firetrust to repair this bug in Mailwasher?
EXPLANATION:
The emails are shown correctly in the Outlook and Thunderbird clients on Windows 11, and I can see the HTML of emails from other sources in Mailwasher. There's something special about the way PostMark uses the multipart MIME format that trips up Mailwasher.
Below is an example of an email message. This is the raw source with the top-most receive/delivered headers removed and the email addresses changed. I took care to keep the empty lines exactly as they were.
Code: Select all
From: info@example.com
Date: Fri, 30 Dec 2022 18:36:12 +0000
Subject: Hello from Postmark!
Message-Id: <3fbdfb17-ea98-4f19-bf90-b763aad3c7fd@mtasv.net>
To: me@example.com
Feedback-ID: s9356667-_:s9356667:a142788:postmark
X-Complaints-To: abuse@example.com
X-PM-Message-Id: 3fbdfb17-ea98-4f19-bf90-b763aad3c7fd
X-PM-RCPT: |bTB8MTQyNzg4fDkzNTY2Njd8d3BkZWpvbmdAdC1tb2JpbGV0aHVpcy5ubA==|
X-PM-Message-Options: v1;9Hcc_PIAriBnYBOfaIwCcyIPcaJJ4QcTBG0Vjf0upsKfpR9qOJtFHrXwPywaBTAW0yivONdmCE8g_Gy1UcqUBBDOwW7mU_BYoMQKRhXnXR0
MIME-Version: 1.0
X-PM-MTA-Pool: transactional-3
Content-Type: multipart/alternative;
boundary=mk3-470f5c3c4d4c47aebbab1dbc28d62e07; charset=UTF-8
--mk3-470f5c3c4d4c47aebbab1dbc28d62e07
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: quoted-printable
This is just a friendly 'hello' from your friends at Postmark.
--mk3-470f5c3c4d4c47aebbab1dbc28d62e07
Content-Type: text/html; charset=UTF-8
Content-Transfer-Encoding: quoted-printable
This is just a friendly <i>'hello'</i> from your friends at Postmark.
--mk3-470f5c3c4d4c47aebbab1dbc28d62e07--
I've ran some tests, and the conclusion is that the problem is the Content-Type header. This header doesn't work in Mailwasher:
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Content-Type: multipart/alternative;
boundary=mk3-470f5c3c4d4c47aebbab1dbc28d62e07; charset=UTF-8
Whereas this one does:
Code: Select all
Content-Type: multipart/alternative;
boundary=mk3-470f5c3c4d4c47aebbab1dbc28d62e07
This is clearly a bug in the way Mailwashes handles the Content-Type header, it should take note of the semi-column separator.
The source for this is RFC 2045 section 5.1:
https://www.rfc-editor.org/rfc/rfc2045#section-5.1.
The special characters are: ()<>@,;:\"/[]?=.