Version:           unknown (using KDE 3.5.7, Kubuntu (feisty) 4:3.5.7-0ubuntu1~feisty2)
Compiler:          Target: i486-linux-gnu
OS:                Linux (i686) release 2.6.20-16-generic

Setup / steps to reproduce:

* KMail connecting via dIMAP to an Exchange 2003 server
* Groupware folders enabled in KMail
* "Calendar via IMAP using KMail" resource in KOrganizer (read only)

Symptom:
Events with attachments do not show up in KOrganizer. They do show up in KMail in the Calendar subfolder of the Inbox subscription folder. They also show up in Outlook and OWA calendars with no problem.

Expected behavior:
Events with attachments should show up in the calendar, ideally giving the option to also open the attachment from within KOrganizer.

Notes:
* All events are created or accepted via Outlook for compatibility reasons. I am mentioning this to eliminate any possibility of KOrganizer creating events improperly.
* The content-type of IMAP messages (calendar events) that show up is multipart/alternative, containing text/calendar and optionally text/plain, text/html etc.
* The content-type of IMAP messages (calendar events) that do not show up is multipart/mixed to accommodate the attachment, with one part being multipart/alternative (text/calendar et al) and the rest being attachment(s)

Speculations:
My guess is that KOrganizer expects a multipart/alternative message containing text/calendar and does not recursively traverse the MIME partition tree. This is a speculation solely based on symptom observation and not source code.