Horde_Mime 2.1.1.

Not going to concern myself whether this is legal or not, since the 
fact is that some people are sending messages this way and it doesn't 
prevent us from correctly parsing the rest of the message.

Changes have been made in Git (master):

commit 08976e0792c6d853b766a51f98baa393bc345239
Author: Michael M Slusarz <slusarz@horde.org>
Date:   Thu Apr 18 14:44:28 2013 -0600

     [mms] Fix parsing wrapped header lines that contain no atom data 
(Bug #12189).

  framework/Mime/lib/Horde/Mime/Headers.php          |    2 +-
  framework/Mime/package.xml                         |   12 +++++++-----
  framework/Mime/test/Horde/Mime/HeadersTest.php     |    8 ++++++++
  .../Horde/Mime/fixtures/header_trailing_ws.txt     |    6 ++++++
  4 files changed, 22 insertions(+), 6 deletions(-)

http://git.horde.org/horde-git/-/commit/08976e0792c6d853b766a51f98baa393bc345239

Yes, I totally agree.  And yes you are correct, RFC 5322 (which itself 
obsoletes 2822) is the current; my apologies.  In section 2.1 General 
Description, it still refers to the separation as an empty line:

    A message consists of header fields (collectively called "the header
    section of the message") followed, optionally, by a body.  The header
    section is a sequence of lines of characters with special syntax as
    defined in this specification.  The body is simply a sequence of
    characters that follows the header section and is separated from the
    header section by an empty line (i.e., a line with nothing preceding
    the CRLF).

Cheers,

Stu

FWIW, RFC 822 is long since obsolete.  RFC 5322 is the controlling standard.

I'll need to look into RFC 5322 to see if this is allowable.  At a 
minimum, this is an example of a sub-standard MUA sending these kind 
of messages (it makes 0 sense to have trailing whitespace in an 
unstructured header).

The solution is to update line, to only strip EOL characters:

$val = rtrim($val, "\r\n");

Using rtrim to determine when to break is invalid per RFC 822, which 
per section 3.1 (http://tools.ietf.org/html/rfc822#section-3.1) states 
headers are separated from the body by a null line; nothing preceding 
the CRLF.  rtrim incorrectly strips tabs, thus skipping the remaining 
headers
https://github.com/horde/horde/blob/master/framework/Mime/lib/Horde/Mime/Headers.php#L647

Example:

S*T*R*I*P*P*E*D
Message-Id: <redmine.journal-1099.20120619084107@contattadev.com>
References: <redmine.issue-263.20120605215949@contattadev.com>
Subject: [Contatta Core Framework - Feature #263] Code - Attachments in Email
        <- H*E*R*E is a TAB and rest is skipped
Mime-Version: 1.0
Content-Type: multipart/alternative;
        boundary=mimepart_4fe09d9362378_71323fc3637fe1b07f1
Auto-Submitted: auto-generated
X-Redmine-Issue-Id: 263
X-Redmine-Site: Redmine
X-Redmine-Issue-Assignee: mario
X-Mailer: Redmine
X-Auto-Response-Suppress: OOF
X-Redmine-Issue-Author: wkey
X-Redmine-Host: officedev.contattadev.com/redmine
X-Redmine-Project: contattazf