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Office 365 Migration Checklist - Preparing for Migration

Migrating to Office 365 can be an easy task, if it is planned correctly. There could be a lot of things to consider beforehand. In this post, we will be going through some pre-requisites in hardware, software, migration and other things which will make your migration as smooth as possible. Irrespective of your Exchange Server version, these checklists will come handy in the planning stage, migration and after migration processes of your journey to Office 365.

Inventory of Resources

The planning stage is the most important stage of migration. As you may know, Office 365, like any other cloud service, is pay-per-use. This means that if you've purchased 10 mailboxes and using only 5 mailboxes, then you're paying extra for mailboxes or services which you don't need.

Let's start by creating a spreadsheet, with a number of sheets in it. The first sheet would have a list of all mailboxes, the owners, size, email addresses and aliases. The second sheet would include all the distribution groups with the name, email address, permissions of send-as and the members. Another sheet would be of the public folders you have with the name and other properties.

The inventory of all the devices used and users owning the device. If you have an inventory system, this would include extracting the name, device specifications like CPU, RAM, Hard Drive, Operating System and Office applications. This would determine what package the user would require, since Windows and Office apps are subscription-based. Of course, it also helps in determining if the device would need to be replaced.

Subscription Assignment

When this exercise is done, having the whole inventory of current setup, the next step is to mark all those mailboxes or services which will be migrated to Office 365. Next stage is the planning of licensing. Now, depending on the kind of setup you want, there are a number of licenses packages to go through. Lately, Microsoft has changed the name of plans, ending up with one service called Microsoft 365, It has three options - Basic, Standard and Premium.

If you have just mailboxes and files, you might want to go with Basic as it comes with a 50 GB mailbox, 1 TB OneDrive and SharePoint. If you would like to have offline Office applications, you would need to go with Standard. If you are going full-scale into the cloud, with decommissioning of all the servers in your premises, then I would suggest to go with the Premium. It features Windows, Offline Office Apps and Enterprise Mobility Suite E3 (EMS). You can also mix and match the plans depending on the needs of the user. There are other plans available, depending on your business needs. But for the sake of the document, I am listing the most generally used.

During the planning, you must also consider the software and user needs. If you are using an older version of Office Apps, you must assign a Standard or higher license so that you ensure compatibility with Office 365. You must have an inventory of all the machine's operating system and Office installation. The Standard comes with all the online features including mailbox, OneDrive and Teams while also having Office installation as a software assurance which means that you don't need to bother with purchasing Office or streamlining the software as everyone will always have the latest version upgraded. If you want to also streamline the operating system you might also opt to other variations of Microsoft 365 like the Microsoft 365 E3 which comes with Windows 10 Enterprise. There are various plans to choose from which would cater for your business needs.

After gathering all the information of what license to assign each user, one can get a good picture of monthly and yearly expenses of the subscriptions. Here, we have the plan of mailboxes to migrate, along with the expenses and license assignment.

Bandwidth and Network

A bandwidth test should be carried out on the main internet connection to ensure that with the number of users the connection will not be crippled. You must also ensure that the ports needed to communicate with Office 365 are open and URL filtering is configured to whitelist Office 365 websites.


For Office 365 migration, one would need to make changes to the internet domain DNS records. Before continuing with the plan, you must ensure that you have a hold of the DNS or the people hosting your service to be prepared to support you with the pre-migration and set up of the domains on Office 365.

Preparing for Migration

Prior to migrate to Office 365, you must first purchase the licenses required and configure the first step to set up the domain on Office 365. This would involve the creation of a text record to confirm ownership of the domain. It will not change anything of the current setup. Once this is done, you can start preparing the local devices by installing Windows 10 and Offline Office Apps, in preparation of the migration. This also includes provisioning of the devices which would be needed for replacing or upgrading the current hardware.

Plan for Data Migration

This is one of the most important things, after the assignment of subscriptions. This will determine if the migration would be a smooth one or a complete nightmare for the technical people involved and the users. There are various ways to migrate the data. This can be done natively by using the Cutover, Staged and Hybrid migration methods. Now, depending on the setup and resources, you might look into which approach to take. It also depends on the version of your Exchange Server. Each approach has its pros and cons and the administrative effort to achieve it.

The easy and minimal effort approach to migrate data is by using a third party tool like Stellar Converter for EDB. With this application, you don't need to worry about the compatibility of your local Exchange Server or extra configuration or resources. All you need to do is attach the mailbox database to Stellar Converter for EDB and with a click of a button export it directly to your Office 365 tenant.

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