New line character after Content-type: causing SquirrelMail to display messages incorrectly

I encountered a problem using SquirrelMail which I wasn't able to solve
using regular means or find in the mailing lists so far. The problem goes
like this - some HTML e-mails are missing contents with the relevant parts
appearing as ATT-n.dat attachments.

I was able to track the problem to the MIME header of the e-mail, namely to
there being a new line character after Content-Type for
multipart/alternative. For example, this e-mail header (I removed the
domain info):

Received: from <IP part>
        (SquirrelMail authenticated user adrian.hada)
        by <webmail> with HTTP;
        Thu, 8 Nov 2012 09:56:41 +0200
Message-ID: f22b0cce2b6dd3c51ff6a39835859b2c.squirrel@domain
Date: Thu, 8 Nov 2012 09:56:40 +0200
Subject:
From: adrian.hada@domain
To: adrian.hada@domain
User-Agent: SquirrelMail/1.4.23 [SVN]
MIME-Version: 1.0
Content-Type: multipart/mixed;boundary="----=_20121108095641_79409"
X-Priority: 3 (Normal)
Importance: Normal
------=_20121108095641_79409
Content-Type:
 multipart/alternative;boundary="7478fsu_trap_90497_14659080112102_=----"
--7478fsu_trap_90497_14659080112102_=----
Content-Type: text/plain
Content-Transfer-Encoding: 8bit

I was able to track this issue to the foldline function in the deliver
class - namely, the long Content-type line causes foldline to do a fold
before the soft limit and sends the rest of the line to the new one. From
there on, I guess the boundary is not correctly interpreted. As a
workaround, I added a preg_match test so that foldLine is not called for
Content-Type lines.

My knowledge of MIME is limited so I can't figure out if the problem is in
the message creation (the newline shouldn't be there) or reception (newline
should be ignored) and I'd prefer to rely on something better than my
quick-fix skills to solve the issue.

Further info:

   - SquirrelMail version - *1.4.23 [SVN] (config file is 1.4.20)*
   - PHP version 5.3.18
   - Web server IIS 6.0
   - HMail Server 5.3.3
   - Windows 2003
   - Installed Manually
   - Browsers - tried multiple

Thanks for your help.


-- 

Adrian Hada

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