We have noticed that when we migrate a user from Exchange to Zimbra and they import prior email (using the pst importer), that all internal mail sent/received while on Exchange places the users name, not their email address, in the headers.

This presents a problem when replying/forwarding a mail that was sent/received while they were on Exchange (of course, they can type in the users email address).

Does anyone know of a solution to prevent this? Anything that they can do on the Exchange side before they create the .pst backup?