My mistake - I didn't have the RTF viewer installed (in Horde).   
However, installing the viewer allows me to view both files perfectly 
fine.  So there is still no bug.

I installed the viewer:



/**

  * RTF driver settings

  * This driver requires UnRTF to be installed.

  * UnRTF homepage: http://www.gnu.org/software/unrtf/unrtf.html

  */

$mime_drivers['horde']['rtf'] = array(

     'location' => '/usr/bin/unrtf',

     'inline' => false,

     'handles' => array(

         'text/rtf', 'application/rtf'

     ),

     'icons' => array(

         'default' => 'text.png'

     )

);



One attachement is correctly displayed when another one is just 
dumping data as you said,  but what I can say: it's not working as 
expected

FWIW, this is incorrect encoding under RFC 2184.  But this has nothing 
to do with the below issue:

That's exactly what is expected.  That is the contents of the text/rtf 
file.  IMP/Horde does not have any specific RTF conversion viewer, so 
it will display the raw contents of the text file.

Hello,



I've noticed a problem using the mime viewer on an rtf file. Somebody 
showed me an rtf documents, and I saw rtf as if there was no data 
transformation, like a dump of the file.



I saved that file, using dimp I sent it to me as an attach doc, then 
click to view it. Guess what, it works.

I then looked at the headers:



This one works well (dimp to himself)

--=_7f4afws2dfgg

Content-Type: text/rtf;

  charset=UTF-8;

  name*="utf-8''D%C3%A9cret%20SCD%2085-694%20en%202009.rtf"

Content-Disposition: attachment;

  filename*="utf-8''D%C3%A9cret%20SCD%2085-694%20en%202009.rtf"

Content-Transfer-Encoding: 7bit



This one does not work

--=_431d1cd1bf52dffeb4eb3d03f4030979

Content-Transfer-Encoding: base64

Content-Type: text/rtf; charset="UTF-8";

  name*="UTF-8''D%C3%A9cret SCD 85-694 en 2009.rtf";

Content-Disposition: attachment;

  filename*="UTF-8''D%C3%A9cret SCD 85-694 en 2009.rtf";



And one is encoded in base 64



and it produces:

{\rtf1\ansi\ansicpg1252\uc1 
\deff0\deflang1036\deflangfe1036{\fonttbl{\f0\froman\fcharset0\fprq2{\*\panose 
02020603050405020304}Times New 
Roman;}{\f2\fmodern\fcharset0\fprq1{\*\panose 
02070309020205020404}Courier New;}

{\f3\froman\fcharset2\fprq2{\*\panose 
05050102010706020507}Symbol;}{\f14\fnil\fcharset2\fprq2{\*\panose 
05000000000000000000}Wingdings;}{\f27\fswiss\fcharset0\fprq2{\*\panose 
020b0604030504040204}Tahoma;}{\f28\froman\fcharset238\fprq2 Times New 
Roman CE;}



To get it the viewer

http://hordetest.univfr/horde/imp/view.php?popup_view=1&mailbox=INBOX&index=28793&actionID=view_attach&id=2.2.2.2&mimecache=213ed84b83d6ad2e046312a5e5e4b307



Dom