When using ZCS Import Wizard for Outlook to transfer emails from Outlook into Zimbra account, we encounter incomplete migration due to either email with huge attachments or network disconnection. Unfortunately, there is no check for duplication. So we can't use it to import again as there are already new emails coming into the Zimbra account.

The workaround we can think of that has a check for duplication is to create a temp zimbra account to import from outlook again. Export it as Zimbra archive and import this Zimbra archive into the user Zimbra account and select replace duplication.

To our surprise, Zimbra import failed to replace duplicates and now there are 2 copies of every emails. What can we do next? Is there an utility to remove duplicate like Outlook add on for Zimbra?

So why did Zimbra Import failed to replace duplicates?