This Answer comes directly from:
Microsoft CSS Online Newsgroup Support:
"Based on my deep research, due to limitations of the IMAP protocol, as well as for efficiency and interoperability concerns, Outlook does not allow non e-mail folder storage on an IMAP server. This means Your Sent Items, Drafts, and Deleted Items folders cannot reside on an IMAP server. Outlook requires that all special folders exist in the default store. This is a by design feature of Outlook and this design is based on the limitation of the IMAP protocol. I am very sorry to say there is no a direct solution to this issue.
"For more information, I recommend you refer to the following URL: OL2002: How to Use an IMAP Account with Outlook 2002 http://support.microsoft.com/?id=287574
"As a workaround, I suggest that you use the Rules Wizard to save sent messages in a folder on the IMAP server. You may want to disable the options to save sent messages in your Sent Items folder. If you do this, you will keep sent messages from being saved on the local PST folder.
"198854 OL2000: (IMO) How to Save Sent Items on an IMAP Server http://support.microsoft.com/?id=198854
"If you have any concerns and questions, please feel free to let me know. Thank you for your understanding."
You could also use Mozilla Thunderbird which does support this feature.
