Office 365 Migration Issues

We just went though a migration from our on premises Microsoft Exchange to Office 365. While the initial migration of users went smoothly, we experienced the following issues:

  • Email migration did not migrate all email messages, but the wizard said the migration was successful and disabled the mailbox on the exchange server. We had to export the mailboxes to PST files and then import the PST files for these mailboxes.

In the Exchange Management Shell, we first need to give a user the rights to import/export mailboxes:

New-ManagementRoleAssignment –Role “Mailbox Import Export” –User Administrator

Next create a shared folder to store the exported PST files. The share needs to give read/write permissions to the “Exchange Trusted Subsystem”.

In the Exchange Management Shell, start the export using the command:

New-MailboxExportRequest –Mailbox username –Filepath \\server\share\username.pst

To view the status of the export:


  • The Azure AD Connect stopped syncing user accounts. We had to reset the password on the account used for syncing to correct the issue.
  • The default Azure AD Connect setup synced the entire AD forest. We limited it to a specific OU to prevent the syncing of machine accounts (printers, service accounts, etc.)
  • A few accounts reverted to their user name.

In Azure Active Directory Module for Windows PowerShell change the User Principal Name using the command:

Set-MsolUserPrincipalName –UserPrincipalName –NewUserPrincipalName


About jasontarby

Enterprise Architect / Network Engineer at SRA International, Inc.
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