Delegated mail stuck in outbox

There seem to be a problem with Outlook 2010 regarding the option to send as a delegated mailbox when running in online mode. Apparently, the mail is sent but it seem to be stuck in the outbox folder of the main mailbox. This only happens in the following scenario.

• Outlook is running in online mode
• A mail is sent from a delegated mailbox
• The registry tweak to move sent mail to the appropriate sent items folder is activated

According to a certain Fiona Liao, this is a known issue within Microsoft and will not be fixed until Outlook 2012. Also, the same problem seem to be present in Outlook 2011 for Mac OS X.