How to Migrate from Office 365 to G Suite: Full Guide

Office 365 Migration to G Suite: Steps to Take


This article covers the Office 365 migration to G Suite using Data Migration Service (DMS). It is inbuilt in Google Workspace (former G Suite), so it is free if you have a paid account. The process is easy but can be time-consuming because of the large amount of data.

Note: if you have more than 5 people to migrate, with DMS the process can be quite a time-consuming task. Also, we want you to be aware that the Data Migration Service has some restrictions. It can’t migrate files from OneDrive. You’ll have to move those files manually or using a third-party tool. Plus, with Data Migration you have to pull over a particular type of data (email/contacts) one at a time, not altogether. 

The second option is to use a third-party backup and/or migration tool. If you back up your data (which we strongly advise you to do), you can use the backup tool as the migration service for all saved data. These tools simplify the migration, especially if you need to transfer many users at once. 

In this tutorial, we migrate email from Office 365 to Gmail, but the process of migrating Calendars and Contacts is the same. 

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Migration from Office 365 to G Suite Using Data Migration Service 

At this point, we assume by default that, by this point, you have already created the destination G Suite account(s). Let’s get started!

Step 1. Set up roles for Office 365 accounts

This is a pre-migration step that makes migration possible. When you are migrating your data, you need to provide your credentials from Office 365 accounts to G Suite Data Migration Service. For DMS to extract data, you need to assign some new roles for your O365 account. These roles are:

– ApplicationImpersonation

– ViewOnly-Configuration

How to do that:

1. Log in to your Office account.

2. Go to the Admin panel. In the desktop version, go to apps and click on Security&Compliance. In the web version, click on Exchange.


3. Go to Permissions section.

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4. In Admin roles block click on +. In the new window, fill out the Name field, go down to Roles and press on + again. Choose the first role (ApplicationImpersonation) and click Add, then repeat with the second one (ViewOnly-Configuration). 

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5. Click on Save.

6. Then, go to the User roles block. Click on + and add your account.

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7. You don’t have to do this with all the accounts you are about to migrate data from – do this just for the account that G Suite will use to connect to Office 365. 

8. Note that the process can take some time to take effect. Wait 10-20 minutes, and then you can proceed with the migration itself.

Step 2. Moving Mails, Calendars, and Contacts

So, let’s start office 365 cross tenant migration with emails.

1. Open your G Suite admin console. Go to Data Migration.

data migration

2. Chose Email.

3. In the Migration source field, select Microsoft Office 365.

4. In the Connection protocol field, chose Exchange web services. There will appear a new field where you need to put a web address of the migrating Outlook account.

5. In the Role account field, type the email address and password of the role account on your mail server.

6. Press Connect.

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7. On the next page, you have to choose a date range and specific email folders to copy. Choose the options that make sense according to your needs. 

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8. Press Select Users.

9. On the new page, you have to specify the source account(s) to transfer data from, and the destination account to move data to. 

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10. Click Start.

It usually takes some time to see the percentage bar movement in the Status column. The amount of time needed to migrate the Office 365 mailbox to another tenant depend on the number of emails. For example, it may take an hour to move 2000 emails. If you have thousands of emails to migrate from different users, be patient, and occupy yourself with other things while waiting for migration to finish.

Remember to backup your business-critical data in Google Workspace!

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