Copy all mail mail to a single user?

[infosyst]

I currently use always_bcc to copy all mail to a single "archive" account. The mail in this account is then pulled off the Zimbra server to an archive server using IMAP. This works great, except for one issue. I have been converting users over and importing their Outlook PST files into their new Zimbra accounts. These messages don't get processed and don't get bcc'd and as a result, don't get archived. Is there any way to copy all of these old messages (or even all messages) to this "archive" account so that they will get pulled to the archive server?