No more exmerge in Exchange 2010, using mailbox import export

First you have to give permissions to the account that needs to import/export or nothing will work. Where “MyExportAccount” is the account that needs permissions to export user mailboxes
New-ManagementRoleAssignment -Role “Mailbox Import Export” -User “MyExportAccount”
Next you must submit the request to export a mailbox(you must export to a UNC path). Where ExportMailboxuserName is the alias of the user you are exporting
New-MailboxExportRequest -Mailbox ExportMailboxUserName -FilePath “Server1PSTExportsExportMailboxUserName.pst”
You may notice if you run the command below that the export status is queued
Get-MailboxExportRequestStatistics ExportMailboxUserNamemailboxexport | fl
If it is queued run this command below
Resume-MailboxExportRequest ExportMailboxUserNamemailboxexport