Ok, you need to configure a POP account on your client. You can make a fake one I guess, but I have plenty of accounts that I can add so I just added a real one.
Then go into your rules configuration. Pull down from the pull down menu your new POP account. Make your rule as you did in your IMAP account (for all messages send a copy to a certain IMAP folder).
When finishing the rule it asked me if I want to apply it to all accounts (This dialogue didn't come up when I was making the same rule under my IMAP account, by the way). I chose yes.
Upon completing the rule I sent several test messages both immediately and after restarting Oultook.
It has never failed to send a copy to my targeted IMAP folder, so I am happy for now. I do hope that they get their IMAP support fixed in the next version of Outlook though.
