I have exactly the same versions. Dont know what else could be.

[root@centos ~]# php --version
PHP 5.3.3 (cli) (built: Aug  6 2014 05:54:27)
Copyright (c) 1997-2010 The PHP Group
Zend Engine v2.3.0, Copyright (c) 1998-2010 Zend Technologies

PEAR version is irrelevant.  It is a package manager and has nothing 
to do with display code.

Michael:

Thanks for your answer. I really want to solve this.

Can you tell me the php and PEAR versionsyou had in the working centos 
installation?

Thanks again.

Ivan

Someone who is experiencing this has to track down the underlying cause.

As mentioned previously, I installed CentOS 6.5 and could not 
reproduce on a default setup so there's nothing more us developers can 
do to track this down.

The other image

Same thing here. ics files are not shown when received in an e-mail. 
But if I reply to the e-mail, now the ics is displayed correctly.

Attached you will find 2 images showing this. Everything else works 
fineas far as tested, in horde, IMP and kronolith.

  On the same Centos i have a working installation of (horde) 3.3.10, 
IMP H3 (4.3.10) and (kronolith) H3 (2.3.4) . There are no problems 
with ICS files in that installation.

Horde 6 installation was made via PEAR. There are no errors in log


/etc/redhat-release
CentOS release 6.5 (Final)

Verified that this works fine on a CentOS 6.5 server with freshly 
installed horde-webmail 5.1.6.

This is irrelevant for displaying the calendar data.

$mime_drivers['itip']['inline'] = true;

is the line that needs to be in there (although it shouldn't be needed 
since itip parts should be displayed inline by default).

I can verify that the sample message attached displays the itip data 
on my installation.

just to be sure:

[root@mail ~]# cat /var/www/horde/imp/config/mime_drivers.local.php
<?php
$mime_drivers['html']['inline'] = true;

good.

however, how would I configure that? would that be in

/var/www/horde/imp/config/mime_drivers.php ?

that file is untouched, i.e.


     /* ITIP (iCalendar Transport-Independent Interoperability Protocol)
      * display. */
     'itip' => array(
         'inline' => true,
         'handles' => array(
             'text/calendar',
             'text/x-vcalendar'
         ),
         'icons' => array(
             'default' => 'itip.png'
         ),

         /* How event replies are handled when a user opens the message.
          *   - false: Reply status is never automatically updated; requires
          *            explicit action by the user.
          *   - true: Reply status is always automatically updated.
          *   - Array: An array of domains for which replies are always
          *            automatically updated. All other domains require the
          *            reply status to be explicitly updated by user action. */
         'auto_update_eventreply' => false,

         /* How free/busy publish data is handled when a user opens the
          * message.
          *   - false: Free/busy data is never automatically updated; requires
          *            explicit action by the user.
          *   - true: Free/busy data is always automatically updated.
          *   - Array: An array of domains for which free/busy data is always
          *            automatically updated. All other domains require the
          *            free/busy data to be explicitly updated by user
          *            action. */
         'auto_update_fbpublish' => false,

         /* How free/busy replies are handled when a user opens the message.
          *   - false: Free/busy data is never automatically updated; requires
          *            explicit action by the user.
          *   - true: Free/busy data is always automatically updated.
          *   - Array: An array of domains for which free/busy data is always
          *            automatically updated. All other domains require the
          *            free/busy data to be explicitly updated by user
          *            action. */
         'auto_update_fbreply' => false
     ),

This seems to indicate that you simply don't have IMP configured to 
handle itip data on your CentOS system.  It is instead displaying the 
previous alternative (the HTML part).

The Debian screenshot is of a system setup to handle itip (i.e. 
text/calendar) data.

text/calendar data has nothing to do with HTML (libxml2) parsing, so 
this is not the same issue as #13122.

screenshot of Debian invitation display

screenshot of RHEL 6 invitation display

attached invitation email was generated using open-xchange. gmail / OX 
will recognize it, however horde will not on our system - will display 
HTML contents instead.

however, same email sent to a friend who is running horde on latest 
stable debian had no trouble viewing + accepting the invitation, so 
probably this is (besides the strange unicode mail encoding problem I 
reported earlier) another case of Horde vs RHEL 6 / php incompatibility?

Is there anything that could be done to improve this (other than 
waiting for CentOS 7? ;)

thanks,

    guenter