Microsoft 365 to Gmail Migration Guide


  1. Microsoft 365 to Gmail Migration Guide with Cloudiway
  2. Security
  3. Performance
  4. Mail migration scope
    1. What can be migrated?
    2. Migration limitations
    3. Considerations
    4. Audience
  5. Pre-migration configuration
    1. Before you start
    2. Source prerequisites
      1. Create source Office 365 service account
      2. Azure Active Directory Application
    3. Target prerequisites
      1. Google IMAP Configuration
      2. Google feeds
      3. Create your user mailboxes
      4. Create your resource mailboxes
    4. Mapping Table
  6. Use the Cloudiway platform to migrate your mail
    1. Create your Office 365 Source and Google Target connectors
    2. Configure the global settings for migration
    3. Import or create your users into Cloudiway platform
      1. Option 1: CSV file import
      2. Option 2: Import Users tool
      3. Option 3: Create a single user
    4. Activate and monitor your migration
  7. Other migration options
    1. Mailbox permissions migration
    2. Resource mailbox Migration
    3. Distribution List migration
  8. Troubleshooting


1. Microsoft 365 to Gmail Migration Guide with Cloudiway

Cloudiway’s mail migration solution helps businesses perform elaborate technical migrations through a simple cloud interface. As a result, mail migrations require no additional software installation or overhead, and migrations can be performed securely and quickly.

The Cloudiway platform is flexible enough to support all types of migration paths. Your migration strategy will depend on your business setup, type, and size. Whichever migration path you choose, Cloudiway provides all the essential features including archive migration, calendar coexistence (Free/Busy scheduling) and contact synchronization (GALSync).

Two of the most common migration strategies are cutover and staged migrations. Cutover strategies involve migrating all mailboxes over a weekend, ready for your users on Monday morning. Staged strategies provide more flexible migration options, as discussed on this page.

Cutover VS Staged: The Best Migration Strategy

Cloudiway has developed a number of tools to enable seamless migration for the most intricate migrations. Our supplementary tools include:

  • calendar Free/Busy display;
  • and, GALSync (Global Address Lists Synchronization).

Coexistence manages cross-platform communication with no impact on the end-user. It provides a seamless connection between two different remote systems during the migration. For example, a Google user can check the free/busy time of an MS 365 user. It also creates all users as contacts on both sides and keep the address books up to date.

These tools are available as additional modules, and therefore incur an extra cost. Please contact us.

2. Security

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

3. Performance

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

4. Mail migration scope

4.1. What can be migrated?

When migrating from Office 365 to Gmail, all the following mail-related items can be migrated:

  • Emails
  • Shared mailboxes can be migrated to a user mailbox with delegation
  • Contacts
  • Calendars
  • Secondary calendars
  • Folders are created as labels
  • Mailbox Permissions
  • Tasks

4.2. Migration limitations

G Suite uses labels rather than folders to organize emails, and users can apply multiple labels to a single email. Office 365 mail doesn’t use labels, so storage for each email is limited to one folder. The Cloudiway platform takes the folder in Office 365 and creates one label with the same name, where the email will be stored.

What can’t be migrated: Rooms and equipment, Journal, Notes, Litigation hold folders, Online archives.

Currently, inbound rules (including out of office rules) are not migrated from Office 365 to G Suite.

4.3. Considerations

Migration takes place between existing mailboxes. This means that mailboxes must exist in the target at the time of migration. Before starting a migration, please ensure that all mailboxes to be migrated have had their target mailbox created in the target domain (steps are included in this guide).

4.4. Audience

This guide is aimed at experienced system administrators who are capable of connecting to remote systems and using a variety of administration tools.

Although we provide support for our own products, we do not provide support for third-party products such as PowerShell or server administration of Google or Exchange.

If you are concerned you might have any difficulty completing these steps, please consider a solution with our consulting team. We will ensure a fast, cost-effective and stress-free implementation.


5. Pre-migration configuration

5.1. Before you start

Before you start, you need the following accounts:

Name Description Location
Cloudiway Account to configure the Cloudiway Platform for your migration.
Google Admin To configure the Google feeds.
Office 365 Admin Used to configure Azure Active Directory Application and associated permissions.


5.2. Source prerequisites

5.2.1. Create source Office 365 service account

To perform the migration, we recommend creating an Office 365 account (service account) with impersonation privileges dedicated to the migration, that can be deleted once the migration is completed. This migration account is used to access the source mailboxes and needs to be provided in a Office 365 Connector. It must be configured with multi-factored authentication (MFA) and SSO (ADFS) turned off. To deactivate MFA On Your Office365 Migration Account (guide:

An Office 365 account can access up to 100 mailboxes concurrently. Therefore, by default, Cloudiway allows you to migrate 100 concurrent users in an Office connector. If you wish to speed up your migration, you should set up additional source Office 365 connectors on the Cloudiway platform and associate different source accounts with admin access to each one. Each source connector will be assigned to the corresponding source connector pool to automatically allocate connectors to 100 users.

5.2.2. Azure Active Directory Application

EWS API calls are performed through an Azure Active Directory Application which is granted specific permissions.

You can either create an Azure Active Directory Application manually or let the platform create one for you (if your migration account is global admin). You need to register one app in the source Azure Active Directories when creating the Office 365 Connector.

Please consult how to create the Azure Active Directory Application and associated permissions.

5.3. Target prerequisites

5.3.1 Google IMAP Configuration

  1. Sign in to your Google Admin console using an administrator account.
  2. From the Admin console Home page, go to Apps > Google Workspace > Gmail > End User AccessGoogle IMAP Configuration
  3. Select the organizational unit you want to configure settings for. If you want to configure settings for everyone, select the top-level unit. Or, select one of the child organizational units.
  4. Go to POP and IMAP access.
  5. Click the pencil “edit” icon.
  6. Check Enable IMAP access for all users. And Select Allow any mail client.
    You do not need to enable POP for Cloudiway tools to work.
  7. Save your settings.

5.3.2. Google feeds

To perform the migration, you need to configure the permissions (Google feeds).

This article explains how to add the Google feeds:

Google Workspace Connector Configuration

If you are already familiar with the platform and the Google APIs, the Cloudiway Google service account client ID: 114818336788408865729. You can also create your own Google service account and enter its client ID.

And, the scope you need is the following:,,,,,,,,

5.3.3. Create your user mailboxes

Cloudiway migrates between existing user mailboxes and does not provides a tool to provision user mailboxes. Therefore, the user mailboxes must be created prior to the migration. You can set up user accounts on the target Google Workspace.

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:

Create Connectors Guide

Office 365 Connector Configuration

Google Workspace Connector Configuration

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 Settings

Most of the options are self-explanatory.

The Convert Email Address option needs further explanation. The Convert Email Address option is switched on by default (and is best left on). When activated, this option rewrites email addresses found in the email headers, calendar items and mailbox permissions and replaces source email addresses with their corresponding target email addresses in the mapping table. Therefore, it’s important that all users exist in the mapping table before migration begins.

Click on the Save button at the bottom of the screen to update your global settings.

6.3. Import or create your users into Cloudiway platform

There are a number of ways to add users that you wish to migrate. These include:

  1. CSV file import.
  2. Cloudiway’s mailbox discover tool (Get List).
  3. Create a single user.

Regardless, each user will need to be assigned a license type — Trial (limited to 100 MB), Education, Standard, Archive, or No License (used for adding users to your mapping table regardless of migration plans).

Note that importing users into Cloudiway won’t create the user mailboxes in the target tenant. See 5.4. Create your user mailboxes

6.3.1. Option 1: CSV file import

If you have a CSV file of all your users, you can upload the file to Cloudiway. The file must have the following fields in the header row:


How To Fill The Users/Groups CSV File?

  1. Ensure you’re still in the Mails Migration area of and go to User List Mail Migration User List
  2. Click on MANAGE and select ImportMail Migration Import User List
  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 O365 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.


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

Get User List

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.

File Migration Get 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:

Create User Mailbox Migration

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:

Delta Pass During Mail Migration

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

Cloudiway 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:

Switch Domain Global Action

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:

Mail Forwarders User Guide


7. Other migration options

7.1. Mailbox permissions migration

You can migrate permissions for mailboxes through the Cloudiway platform.

Migration of permission isn’t performed during the migration of the mailboxes but through a dedicated job.

The migration of the permissions will migrate permissions on the mailboxes, on the primary and secondary calendars.

Click on User List, select the users, go to MIGRATION, then click on Migrate Permissions

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:

Rooms and Equipment Migration

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:

Distribution List Migration in Office 365


8. Troubleshooting

Cloudiway provides an extensive Help Center, also known as knowledge base, with many resources, including common error messages, guides, and downloads.

Please visit the Help Center here (where you can search for keywords or read through topics):

The Help Center also contains information on how you can ask for further support.

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