1. Microsoft 365 to Gmail Migration Guide with Cloudiway

2. Security

For more information about security, please refer to this article.

3. Performances

For more information about migration performance, please refer to this article.

4. Mail migration scope

5. Pre-migration configuration

CloudiwayAccount to configure the Cloudiway Platform for your migration.
Google AdminTo configure the Google feeds.
Office 365 AdminUsed to configure Azure Active Directory Application and associated permissions.
Google Workspace Migration

The Cloudiway Google service account client ID is: 114818336788408865729. 

But you can also create your own Google service account and give it the necessary permissions.

The scope to authorize are:


5.3.3. Create your user mailboxes

Cloudiway migrates between existing user mailboxes. Therefore, the user mailboxes must be created prior to the migration. 

5.3.4. Create your resource mailboxes

Resources from your source must be available on your target before migration can begin. Cloudiway provides a tool to automatically recreate rooms and equipment for migrations from Office 365 to G Suite, which will be explained later in this guide. Cloudiway can also recreate shared mailboxes in the target. If you’d like a preview, please get in touch with our team of experts.

5.4. Mapping Table

During the migration, Cloudiway uses a mapping table to perform the conversion of email addresses in email headers, calendar items and mailbox permissions.

Important: the mapping table must be exhaustive, any missing email address will not be converted, and would end up with loss of mailbox permissions, unreplyable emails and broken calendar items. Cloudiway automatically populates this mapping table when source mailboxes are discovered by Get List functionality explained below. However make sure if the mapping table was populated automatically that you are not missing any email address.

6. Use the Cloudiway platform to migrate mailboxes from Office 365 to G Suite

6.1. Create your Office 365 Source and Google Target connectors

For Cloudiway to migrate your email, it needs to be able to communicate with both your source (Office365) and target (GSuite) domains. To do this, Cloudiway uses connectors. You will need to set up a connector for each source tenant you wish to migrate and each target tenant that mail should be migrated to.

Follow the steps on the page below to configure an Office 365 source and GSuite target connector:

For large projects, it’s possible to create multiple connectors that will be used in parallel. Please contact Cloudiway consulting services if you need to set up such configuration.

6.2. Configure the global settings for migration

Now that you have set up at least one source and target connector, you’re ready to configure your global settings. Using the Cloudiway platform, this is simply a matter of selecting what you want to migrate.

From the Mails area of, click on Global Settings

Mail Migration Global Setting
1. Ensure you’re still in the Mails Migration area of and go to User List
Mails migration UserLists
2. Click on MANAGE and select Import
Mails migration UserList Import
3. If required, click on Download sample CSV and add your users to the CSV file using the sample headers (FirstName; LastName; SourceEmail; TargetEmail; SourceRecipientType; TargetRecipientType; BatchName)
4. When you have a complete CSV file with the correct headers, click on the BROWSE button
5. Locate your CSV file within your own file system, and double-click on it to select it
6. Select the appropriate connectors in the Source and Target fields
7. Click on the UPLOAD button.
Import Office 365 to Google mail migration
8. If you see any error messages, check your CSV file to ensure it has seven columns, each with a separator (including the last) and try uploading again.

6.3.2. Option 2: Get List

Cloudiway’s Get List tool helps you to retrieve mailboxes from your source tenant. There are 5 Get List tools corresponding to the different sections:

  • User List: to discover only user mailboxes.
  • Shared Mailboxes: to discover only shared mailboxes. In Google does not exist the concept of shared mailbox as in Office 365, so you can migrate Office 365 shared mailboxes to a user mailbox and apply mailbox permissions.
  • Room Equipment: to discover only resource mailboxes.
  • Distribution list: to discover only distribution lists.
  • Archive: to discover only archive mailboxes. In Google you would have to migrate archive mailboxes to a user mailbox.

Go to User List, Room & Equipment or Distribution Lists sections and then click on Migration, select Get List.

Get list

The tool requires you to enter the Source and Target Pool.

Get User List Office 365 to Google mail migration

Then to specify:

  • The Matching Rule:
    • Mail Exact Match: the source email = the target email ( >
    • Keep Email Prefix Same as Source: only the domain name changed ( >
    • FirstName.LastName (i.e.
    • F.LastName (i.e.
    • FLastName (i.e.
    • LastNameF (i.e.
  • The Target Domain.

It will then add new users to the User List. You can monitor the progress of this task in the User List: Get List Logs.

Cloudiway User List Logs

6.3.3. Option 3: Create a single user

Many of our first-time customers create a single user for testing purposes. This provides a means of watching the migration process without affecting all users.

Click on MANAGE > Create User and enter the following details:

Mails migration Create User

For more information regarding the different fields, check out this article. Repeat the process for any more users you’d like to create.

6.4. Activate and monitor your migration

Cloudiway is an incremental migration platform that supports delta passes. Every time you restart the migration of a mailbox, only items that haven’t already been copied to the target will be migrated and for those already migrated items that have been modified in the source will be updated in the target. The platform, therefore, does not duplicate items in the target, just updates them.

The migration strategy usually consists of at least 2 migration passes, one before the cutover and another pass after the cutover:

  • 1st migration pass: which migrates the majority of the mailbox. Select mailboxes, click on MIGRATION, then the Start button. Explained below in more detail.
  • Cutover: You have to manually remove the domain from the source tenant, attach it to the target tenant and change the MX record in your DNS server. This is not automated by Cloudiway.
  • 2nd migration pass, delta pass: which migrates what hasn’t been migrated and updates modified items. Select mailboxes, click on MIGRATION, then the Start button. Explained below in more detail.
  • 3rd migration pass, delta pass: 24 hours after cutover you can submit an additional delta pass to make sure no residual email is left behind due to DNS propagation delays. Select mailboxes, click on MIGRATION, then the Start button. Explained below in more detail.

You can submit as many migration passes as you want for 3 months and until consuming the amount of GBs allowed by the assigned licenses but usually, you only need one before the cutover and another after the cutover. Find out more about the delta migration passes:

What a migration pass takes to complete depends on a lot of factors. Find out more about the migration performance:

If you have moved the source domain and need to perform one more delta pass, the Switch Domain global action will need to be used:

You can create user batches from the Batches tab to easily group subset of mailboxes. Click on the + icon and enter a batch name:


After creating the different batch, under Users tab, select the users you want to assign to a specific batch, click on BATCH button and Add to Batch:


To start your migration, select the users or batch you wish to migrate.

  • For users, under Users tab, select all the users you want to submit and click on MIGRATION, then the Start button.
  • For user batch, under Batches tab, select the user batch you want to submit and click on MIGRATION, then the Start button.

Your migrations will be scheduled and will begin as soon as cloud resources are available.

NOTE: When migrating by user batches during a long period of time you may want to enable email forwarders.

For more information, please see this article:

7. Other migration options


NOTE: Once you start the process of permissions migration, it cannot be stopped.

7.2. Resources Migration

From the Rooms & Equipment section under Mail, you can recreate and migrate resource mailboxes from your source tenant to your target tenant.

For more information, please see this article:

7.3. Distribution List migration

From the Distribution Lists section under Mail, you can recreate and migrate distribution lists from your source tenant to your target tenant.

For more information, please see this article:

8. Troubleshooting