8 Tips for a Smooth Office 365 Migration

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8 Tips for a Smooth Office 365 Migration

Office 365 migrations can be extremely complex, with many moving parts. They can include risks such as severing delegate relationships, cutting executives off from their calendars, cutting admins off from their executives’ calendars, mismatching user data across a large number of systems, disconnecting credentials, and more. 


Whether you’re migrating from on-premises Exchange to the cloud or moving from a legacy Office 365 tenant to a new one, or because mergers and acquisitions have left you with a mix of on-premises, hosted Exchange, and Office 365 deployments, early planning and effective tools will be crucial to your success. 

While Microsoft provides several migration-related tools, none of them will be enough on their own to effectively plan and complete your migration. That’s why many migrations end up utilizing a large number of spreadsheets and manual data entry. These processes are error-prone, time-consuming and resource-intensive. 

 A successful migration requires the right combination of planning, data gathering, communications, execution, and reporting – and the right tools for each phase. You can make your migration smooth – for IT and for end-users – with several tips: 


1. Form the big picture about your migration  

  • What exactly are we migrating to Office 365? Email only? Office applications? Files, folders, and file structures? 

  • Who are we migrating and what are the relationships and dependencies? Shared mailboxes? Shared calendars? Permissions? 

  • How are we migrating them? One at a time or in groups based on relationships and dependencies? 

  • Do we have to migrate SharePoint and/or OneDrive for Business? 

  • Do we have to migrate Microsoft Teams? 

  • Do we have recordings stored in Microsoft Stream that need to move with users and groups? 

  • Are we only migrating on-premises systems to O365, or are we migrating from one O365 tenant to a different one? Do we have to migrate hosted Exchange? Do we have a mix of sources? 

  • Do we have advanced implementations of Exchange Online, SharePoint or Microsoft Teams that will require special attention for migration? 

  • What compliance and regulatory requirements must we adhere to, such as legal holds, locked email boxes or accounts, GDPR or CCPA regulations, or simply corporate requirements about where data is physically stored? 

2. Collect accurate and up-to-date details on each user in one place

Most likely, user details are spread out among a variety of Exchange environments, possibly multiple Active Directory domains, as well as spreadsheets, human resources files and other systems. This includes not just user data, but also service configuration and permission settings, mailbox sizes, and more. You’ll need an inventory of every mailbox from each Exchange or existing O365 environment, as well as every user’s data in every environment. As users are onboarded or leave, change departments, or have their permissions and access changed, you’ll need a method for keeping this information up to date. The most crucial step in your migration is to gather all of this information in one place and keep it up to date. 

Additionally, your organization may have one or several mailboxes on legal hold. Their data needs to be retained and the mailboxes cannot be changed. Moving a mailbox that is on legal hold can trigger a compliance or legal event, so you need full visibility into and control of mailboxes in this state. 

3. Map delegation and other interdependencies between mailboxes and calendar

One of the biggest pain points in Office 365 migrations is the relationships between mailboxes, and between mailboxes and users. A typical migration will include around 10% to 20% more mailboxes than users, due to shared mailboxes, group mailboxes, group calendars, and other resources. 

Delegates, calendar sharing, and other interdependencies are typically extremely important to end-users. An admin may be supporting multiple executives, with various levels of access, from read rights to full rights. An executive may have multiple delegations, also at different access levels. 

It can be quite painful for everyone if, for example, an executive is migrated but her admins can’t access her mailbox, or the executive can’t access shared calendars. Up-to-date information about this web of interdependencies must be regularly collected from multiple sources. In addition, you’ll need a reliable way to map those interdependencies so you can plan your migration with as little disruption, and pain, as possible. And, of course, you need a way to keep that data up to date. 

4. Collect and organize data related to SSO and other logins tied to email address, SMTP address, Exchange, and Office 365

Credentials may be the bane of your existence – and of end-users’ – and they could become more complicated during and after a migration. Moving your users’ personas to O365 may impact login to everything from SharePoint and OneDrive to Okta, Teams, and a variety of other single sign on (SSO) and web applications. To minimize these disruptions, make sure to have a complete set of data for each user’s login protocols for all resources they use. Use that data to either update login protocols or set new protocols, and to let each user know if their login protocol has changed post-migration. 

5. Correct data mismatches 

It’s not uncommon to have data mismatches between a user’s Active Directory accounts and Exchange Mailbox. Identifying and correcting these mismatches before a migration can prevent a variety of headaches, from severed connectivity to a total migration failure. 

6. Use data to plan your migration

With a clear picture into who and what you’ll be migrating, you can plan a migration to mitigate the risks and minimize the pain. Some of the key data points to take into consideration as you determine which users and mailboxes will migrate when include: 

  • Maintaining delegate relationships, shared calendars, and other dependencies during the migration. 

  • Whether it makes sense to migrate some services before others. 

  • How much time it will take to migrate each group of mailboxes, based on their sizes.  

7. Let end-users know what to expect

Communicate with end-users before, during and after the migration. Set expectations about how scheduling will work, what will change after the migration, what might not migrate at all, and other service changes (such as changes in mailbox policies, auto-deletion policies, or device access). By setting expectations in advance and reminding users that some changes are normal, you can reduce the volume of help desk inquiries and general frustration. Still, make sure users know who to contact for support. 

8. Identify what is ready for migration and report on migration status

You’ll want to produce a number of reports during and after your migration, including: 

  • Readiness Reports to hand off to engineering. 

  • Migration success reports.  

  • Failure reports (so you can manually migrate anything that didn’t successfully migrate). 

  • Report of users’ post-migration configurations and permission settings. 

  • Compliance reports showing that you’ve preserved files, mailboxes and machines as required for legal holds and other scenarios. 

How ReadyWorks helps you handle O365 migrations: 

In the past, planning an O365 migration would likely have involved several manually compiled spreadsheets that would be out of date soon after they were finalized. And executing it would involve complex orchestration of software tools, a lot of IT personnel, countless emails to end-users, and plenty of risk. 

ReadyWorks is a single command-and-control center for planning, executing, and reporting on Office 365 migrations. While Microsoft’s own migration tools focus only on migration readiness, ReadyWorks helps you plan, prepare for, and execute the migration. It works with all of Microsoft’s tools through bi-directional, native connectors to on-premises and hosted Exchange systems, as well as Office 365 tenants. 

ReadyWorks automatically gathers and constantly updates a full picture of each user, their interdependencies and connections, as well as group mailboxes and calendars, legal holds, mailbox sizes and more. It offers a centralized view of data, complete with mapped dependencies, hierarchies, and other relationships. No more manually compiled and updated spreadsheets! 

 As your migration process moves from planning to preparation through migration and post-migration cleanup, ReadyWorks moves with you. You can use it to automate personalized communications to end-users at each stage; plan, review and execute migration processes; troubleshoot migration failures; and report on successes. 

 By automating the data-gathering, migration, and reporting process in a single tool, ReadyWorks vastly reduces the risks, resources, and time for an Office 365 migration. It gives you clear, up-to-date visibility into: 

  • Data mismatches 

  • Delegate relationships and other dependencies, hierarchies, and relationships 

  • Mailbox sizes and migration times 

  • Legal holds 

  • Group resources 

  • Login and SSO mismatches 

  • Migration waves that will minimize disruptions and maximize the chances of success 

  • Workflows that will maximize use of resources 

  • End-user communications 

  • Migration completions and failure 

Our clients have found ReadyWorks makes their migrations less painful, more accurate, less expensive, and faster. Learn how ReadyWorks can help you save months of labor and significantly reduce 0365 migration costs. Schedule a demo today. 



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