Getting Ready for an Office 365 Mail & File Migration

by | Jul 7, 2020 | Collaboration

Have you been on the fence about moving to Office 365?  Here is some housecleaning you can do in your environment that will help get you ready for the migration. 

Preparing Your Environment

There are several key aspects of most existing environments you will need to verify and clean up prior to migrating to Office 365. 

  • Upgrading Exchange – Organizations still using Exchange 2007 will find they have a hard time migrating to Office 365 without interruption.  The product has not been supported since 2017, and organizations on Exchange 2010 will find similar issues starting in October of 2020.  Making sure you are on a supported version of Exchange will make creating hybrid environments easier and the entire migration process smoother.  Fortunately, a currently supported Exchange server license is available for those who commit to migrating to Office 365, and is included without additional cost for organizations that have active Office 365 subscriptions to support hybrid environment.  You also need to make sure you’re on at least the next to latest cumulative update for supported Exchange versions per 

  • Clean up Active Directory  Many organizations that have been using Exchange servers for a long time will find that there are remnants of improperly decommissioned Exchange servers still lingering within their Active Directory.  It is also recommended you purge your local Active Directory of deprecated accounts if you are synchronizing it to Office 365.  This can minimize initial synchronization errors when configuring Azure AD Connect.  Removing remnants of no longer running Exchange servers can reduce issues setting up hybrid servers and Azure AD Connect.  The most common and recommended methods for removing remnants of dead Exchange servers require accessing your Active Directory through ADSI Edit – this can be extremely risky to your environment.  We highly recommend contacting experienced professionals, such as those at Peters & Associates, if you are not familiar with these kinds of tools. 
  • Prepare file migrations  As OneDrive and SharePoint Online have matured, more and more organizations are looking to migrate flat file and internal websites to these Office 365 services.  Roaming and redirected profiles will need to be temporarily disabled if they will be redirected to OneDrive.  On-premises SharePoint sites have several options depending on your configuration for migrating to SharePoint Online, as per Microsoft’s documentation here  Most organizations do not have the necessary SharePoint migration expertise for a seamless migration experience, so we recommend contacting a capable partner, such as Peters & Associates, to assist with the migration. 

Preparing Your Users

After preparing your environment for migrating to Office 365, there are a number of things you can do to prepare your users as well. 

  • Azure AD Connect Preparation  Many organizations find synchronizing their existing Active Directory users to Azure AD for use in Office 365 to be quite beneficial.  Azure AD Connect can be used for password hash synchronization, multi-factor authentication, and several other benefits.  However, this requires your users in your on-premises Active Directory to be configured a specific way for best results.  First, you will ideally use an internet routable UPN suffix that can be verified with Office 365.  This allows user UPNs to be used, instead of an Alternate ID, for synchronization processes, and simplifies the login process.  Depending on how your organization is configured, this may be a major migration step and require outside assistance.  Second, you’ll want to configure a test group, and instead of using the entire domain as a default (or all forest domains, if in a multi-domain forest) configure synchronization based on the group.  Preparation and determination of which users should be in that group, and whether it is to expand during the testing process, should be determined prior to initial configuration as a part of the migration road map.  This can be either an OU or a security group.  Users also need to be unique across the organization or must use a unique attribute other than their UPN for synchronization if it is to be used as the source anchor.  IdFix is a tool provided by Microsoft that can assist with identifying potential issues with your existing Active Directory configuration when preparing to migrate.  More information regarding that tool and recommended resolution steps can be found here 

  • Office Application Configuration – Depending on the licensing your organization decides, you may not have Office 365 desktop applications to use.  For some organizations, the online applications included in even the basic subscriptions will be fine.  For others, however, a version of the desktop applications will be required.  Organizations utilizing desktop versions of Microsoft Office older than currently supported Office 2016, will need to upgrade those as well if you want to avoid potential issues with Office 365 service compatibility. 
  • Cleanup Data – When migrating user data to OneDrive, the initial data migration is significantly smoother and faster if you’re not migrating old disabled user data and unnecessary data built up in active user profiles that have been around for a while.  Users should either migrate unneeded data to a proper archive or purge their data within your organizations retention policies.  Decreasing the data migrating to Office 365, and then back down to your users, will considerably decrease migration day headaches. 

These are just some of the preparation steps needed for a modern Office 365 migration, and of course every organization has their own, more specific needs.  If you want more information or assistance in planning or executing your migration, email We are happy to help! 

For additional resources, check out this blog from our partners at Interlink Cloud Advisors.