Zimbra Collaboration Suite 7.0
Zimbra Collaboration Suite 7.0
Migration Wizard Guide for Microsoft Exchange

Migrating from Microsoft Exchange to Zimbra Collaboration Suite > Using the ZCS Migration Wizard

Using the ZCS Migration Wizard
Even though the ZCS Migration Wizard can be run from start to finish without stopping, Zimbra recommends that after the accounts are migrated you stop. Before proceeding, change the mail relay information to point to the Zimbra server instead of the Exchange server. This will prevent any lost mail while the files are being imported.
After the files have been imported to the Zimbra server, you should verify that the import was successful before deleting the Exchange accounts.