This guide explains how to migrate from G Suite (Gmail API) to Exchange Online (Microsoft 365) using the Microsoft Graph API. It covers the required configuration steps and migration workflow, along with additional resources to support a successful transition.

MigrationWiz

MigrationWiz is a migration tool, not a syncing tool. If changes are made at the source after migration, they will not sync to the destination, nor will changes made at the destination sync to the source. We do not have “live” monitoring of changes (as with a sync agent) and we cannot handle scenarios such as conflict resolution without user interaction.

First time?

This migration guide contains the necessary steps to perform the actual migration, but there are many steps to preparing for migration. If this is your first time performing a migration, we have created a Migration Planning & Strategy Guide to walk you through planning, set-up, and general migration best practices. If you have never performed a migration before, we suggest reading that before beginning the steps outlined in this scenario.

Prerequisites

It is important to highlight and meet the following prerequisites for a smooth migration project.

Licensing

We recommend that you purchase User Migration Bundle licenses for this migration scenario. User Migration Bundle licenses allow the performance of multiple migrations with a single license. For questions on licensing, visit Which Migration License Do I Need?.

To use your license by following the next steps:

1. Review Considerations.
2. Purchase Licenses.
3. Create a Customer.
4. Apply Licenses.

Limitations

• When migrating from G Suite as a source, contacts in Contact Groups (which look like subfolders of the Contacts folder) will migrate to the top-level contacts folder on the destination. Folders will be created for each group but the contacts will not be sorted into those folders.
• Calendars can have multiple Owners. An Owner is anyone with "Make changes and manage sharing" permissions, so shared calendars will be migrated to users with these permissions by default.
• Due to Microsoft limitations, using Delegate Permissions with Graph API is not supported at this time. Only Application Permissions can be used.
• Pinned/Flagged Emails are migrated but not Pinned/Flagged in the destination environment.
• Threading (email messages that belong to the same conversation) is not supported and will require Manual implementation. 
• Delegate-level calendar access isn't supported by Microsoft Graph. It's automatically downgraded to Free/Busy-only.
• Archive Mailbox as a destination is currently not supported. Support for this option is planned for a future release.

Migrated Items

Please click the bars below to check the migrated and non-migrated items. We are constantly working to create a better migration experience for you so these items may change over time.

Preparing the Source Environment

The G Suite (Gmail API) source endpoint requires your tenant service account to be set up and Google APIs to be enabled.

Prerequisites

• Subscription to Google Cloud Platform.
• Google Super Administrator account.
• Ability to set up a service account on the G Suite tenant.
• Service account must be set up before the MigrationWiz project is created.
• All accounts being migrated must be in Active status in the tenant. Users that are set to a status of Inactive will not be able to fully migrate and will fail in the project.

Create a Google Project

1. Go to the Google Cloud Platform (GCP) Console and sign in as a super administrator. Choose one of the options below:
   • If you haven't used the Google Cloud Platform Console before, agree to the Terms of Service and click Create Project.
   • If you have used the Google Cloud Platform Console before, at the top of the screen next to your most recent project name, click Down to open your projects list. Then, click New Project.
2. Enter a project name and click Create.

If you are not able to create a project here, it may be that the ability to create projects has been disabled for your tenant. To check this, navigate to the Google Admin Center, click on Apps > Additional Google Services, and select the Google Cloud Platform. Once there, you should see a setting that can be toggled to allow users to create projects.

Enable APIs for Service Account

1. From the Google Cloud Platform Console, click Menu () > APIs & Services > Library.
2. Enable the following APIs by selecting the specific API and clicking Enable. Repeat for each API:
   • Google Calendar API
   • Gmail API
   • People API
   • Contacts API
   • Admin SDK

Make sure that the Gmail, Calendar, and Contacts services are enabled within the Google tenant. You can control services for your users by following the instructions on this page: G Suite and Google Services Access.

Create a Customer Tenant Service Account

From the Google Cloud Platform Console,

1. Click Menu > IAM & Admin > Service accounts.
2. Click Create Service Account and enter a name.
3. Click Create.
4. Assign the role of Owner to the new Service Account by selecting Owner from the Role Dropdown menu.
5. Click Continue.
6. Click Done.
7. Click the three dots to the right of the service account and click manage keys then select Manage Keys > Add Key >Create new key.
8. Make sure that JSON is selected and click Create.
   • Make sure that you download the key as a JSON file and make a note of the name and location of the file. This JSON file will be used when setting up the migration endpoint in the Mailbox Migration project.
   • The JSON file must contain information in the following fields: “type”, “private key”, and “client email”. If these mandatory fields are empty the file upload during endpoint creation will fail.
9. Click Close.

Find your Unique ID

From the Google Cloud Platform Console:

1. Go to Menu > IAM & Admin > Service accounts.
2. Find the service account set up in the Create a Customer Tenant Account section.
3. Find the Unique ID field for that service account by clicking the Column Display Options “|||” button in the upper right corner above Actions.
4. Select the Unique ID checkbox.
5. Click Ok.
6. Copy the unique ID number.
   • This is the Client ID number that will be used in a later step.
   • This Client ID should be considered similar to the Administrator account passwords and handled securely.

Setting the Scopes for the Migration

1. Go to https://admin.google.com and authenticate as a Super Administrator.

2. In the admin console, go to Menu > Click Security > Access and data control > API controls > Manage Domain Wide Delegation.

   Important

   If you do not see the security icon on your admin console home page, your account does not have the necessary rights to make these changes.
   Google limits settings access and configuration to only G Suite Super Administrator accounts.

3. Click Add New.
4. In the Client Name field, paste the Unique ID copied above.
5. Enter one of the following groups of scopes into the OAuth Scopes (comma-delimited) field, depending on whether G Suite is the Source or Destination.
   G Suite as the Source (read-only scopes)
   https://mail.google.com/, https://www.google.com/m8/feeds, https://www.googleapis.com/auth/contacts.readonly, https://www.googleapis.com/auth/calendar, https://www.googleapis.com/auth/calendar.readonly, https://www.googleapis.com/auth/admin.directory.group.readonly, https://www.googleapis.com/auth/admin.directory.user.readonly, https://www.googleapis.com/auth/drive, https://sites.google.com/feeds/, https://www.googleapis.com/auth/gmail.settings.sharing, https://www.googleapis.com/auth/gmail.settings.basic,https://www.googleapis.com/auth/contacts.other.readonly 
6. Click Authorize.

You should now see your specific Unique ID and the scopes listed, similar to what is shown below:

Preparing the Destination Environment

Modern Authentication Requirements

The KBs listed in the Exchange Online Authentication options using Graph API section will help you configure the destination tenant when using Microsoft 365 with the Microsoft Graph API. A Global Administrator account is required to consent to the BT app or create and consent to the BYO app, since the Entra app's permission types require global admin approval.

Export the User List to a CSV File

This can be used when bulk-adding users to your MigrationWiz project later. You can copy and paste the user list into the Source and Destination Email columns within your MigrationWiz project dashboard under Add > Bulk Add.

To export the user list:

1. Go to the Microsoft 365 admin portal.
2. Click Users.
3. Click Active Users.
4. Click Export.
5. Click Continue.

Be sure to save the CSV somewhere you can access it for upload later in the migration.

MigrationWiz Steps

Create a Mailbox Migration Project

1. From the MigrationWiz dashboard, click Go To My Projects.
2. Click Create Project.
3. Select a Mailbox migration type. 
4. Click Next Step.
5. Enter a project name and select a Customer from the list. If the customer has not been created yet you can do it here by clicking New, providing the required details including primary email domain and company name, and clicking Save.
6. Click Next Step.
7. Click Next Step.
8. Select endpoints or follow the steps below to create new ones.
9. Click Save and Go to Summary.

Endpoints

Endpoints are created through MigrationWiz. If you select an existing endpoint from the dropdown, it will only show ten endpoints. If you have more than ten, you may need to search it.

Consider that endpoint search is case and character-specific. For example, Cust0mer will not show up if the search is customer. We recommend keeping a list of endpoints you have created, along with any unique spellings or capitalization you may have used.

Create your Endpoints

Please review the following tabs to create your destination and source endpoints.

Add Users

Add the accounts that will be migrated, which are also referred to as items, to a project using one of the following options:

Advanced Options

Support Tab

• InitializationTimeout=8 This increases the initialization timeout window to eight hours. This value is in hours, up to a maximum of 100 hours. Values above 100 are in milliseconds. For example:​
  • InitializationTimeout=2 will increase the timeout to 2 hours.
  • InitializationTimeout=8 will increase the timeout to 8 hours.
  • InitializationTimeout=14400000 will increase the timeout to 4 hours.
  • InitializationTimeout=21600000 will increase the timeout to 6 hours.
• SuppressMeetingInvitationException=1 When migrating calendar invitations, the MIME content of the mail body confuses EWS and can slow the migration. This support option ensures that calendar invitations are migrated without throwing that exception.  All calendar invitations are created correctly on the destination even though EWS throws this exception.

• MigrateHiddenInvitations=1 If your source consists of hidden invitations in a primary calendar that need to be migrated to the destination, please add the advanced option to enable those to migrate since they are not migrated by default. This advanced option is currently available only for G Suite (API) to Exchange Online (Microsoft 365) mailbox migration projects.

  Important

  Invitations migrated will not maintain a hidden status when using the support option.

Bulk Load

To upload a large list of Advanced Support options, see the Bulk Load - Advanced Options when Migrating Mailbox projects using Graph API for additional guidance.

Default Options for Microsoft 365 Endpoints

By default, some fields are view-only. In other words, you cannot edit or remove them from the support options page. To edit them, you need to edit the source or destination endpoint of your project.

Among these default options, you can find ModernAuthClientIdExport, ModernAuthTenantIdExport, ModernAuthClientSecretExport, ModernAuthClientIdImport, ModernAuthTenantIdImport, and ModernAuthClientSecretImport. 

The support options above are required when configuring your endpoint.

Migrating Gmail Labels

Two Advanced options are available to handle the migration of Gmail labels to the destination.

1. Convert Labels to Folders: With this option, user labels from the source are converted to folders at the destination and mails are duplicated in each of their corresponding folders at the destination.

2. Convert Labels to Exchange Categories: With this option, a single copy of all source mail will be migrated to a custom destination folder titled All Mail. All labels from the source are converted to Exchange categories and marked on each item at the destination. 

Migrating Suggested Contacts (Other Contacts)

There are two recommended options, outlined in MigrationWiz - Email Migrations - FAQ.

1. Migrate Suggested Contacts (Other Contacts): Contacts appearing under the ‘Other contacts’ label in Google Contacts will be migrated to the destination folder 'Suggested contacts'. These will not appear under primary My Contacts.

2. Skip Suggested Contacts (Other Contacts): Contacts appearing under ‘Other contacts’ label are not migrated.

Run Migration

The following sections will guide you through running your migration. Each header is one step, with its component steps below. Follow these steps in order, and read the notes for important information about dependencies or best practices.

Run Verify Credentials

1. Open the project containing the items you wish to validate.

2. Select the items you wish to validate.

3. Click the Start button in your dashboard.

4. Select Verify Credentials from the drop-down list.

5. Once complete, select the Status section and view the results of the verification.

Assessment

1. This is an optional step but allows you to retrieve the total folder and item count for the mail items in Gmail.

2. Open the project containing items you wish to assess.

3. Select the items you wish to assess.

4. Click the Start button in your dashboard.

5. Select Assessment from the drop-down list.

6. Click the bar chart icon in the MigrationWiz dashboard to receive an email containing all the project migration statistics.

7. Review the line items folder and mail count.

   1. Mailbox Size (bytes) will show the combined size assessment for selected item types (i.e. mails and/or contacts and/or calendars)

   2. Folder Count will show the combined count for emails, contacts, and calendars

      • Note that this is the total amount of folders, not the item count within the folders
8. See The MigrationWiz Assessment Tool article for more details.

Notify Users

Send out the final notification that the migration is beginning. Include when the migration will start, the expected duration, any usage instructions during migration, and any expected steps or notifications for the post-migration timeline.

Pre-Stage Pass

1. Select the users.

2. Click the Start button from the top, and select Pre-Stage Migration.

3. Under the Migration Scheduling section, from the drop-down list, select 90 days ago.

4. Click Start Migration. 

MX Record Cutover

Once confirmed that the Pre-stage migration has been completed successfully. Log into the DNS provider's portal, and change the primary MX record to reflect the DNS settings for the destination O365 tenant.

Full (Delta) Pass

1. Select the users.

2. Click the Start button from the top.

3. Select Full Migration.

4. Select/ Unselect check boxes (for Contact, Calendars, Mails) based on your migration need.

5. Click Start Migration.
   This migration should be completed quickly since most data is migrated during the Pre-Stage migration. 

Run Retry Errors

Each error logged represents an item that was not migrated. MigrationWiz contains a mode in which you can resubmit the migration to retry failed items. This mode of operation is always free of charge. You may only submit mailboxes in this mode only if they satisfy all of the following conditions:

1. The last migration was completed successfully.

2. The mailbox contains at least one error.

If your mailbox does not satisfy these conditions, you will receive a warning when submitting the migration in this mode and your request will not be fulfilled.

To submit one or more mailboxes in retry mode, perform the following steps:

1. Select the mailboxes that have migration errors.

2. Click the Start button.

3. Select Retry Errors from the menu.

4. Click the Retry Errors button.

When errors are repaired, they will disappear from the error log. Some errors may not disappear if the Source item was not reprocessed (due to filters, for example), has been deleted or moved, or if the item failed again.

Final Steps

Users must create new Outlook profiles, set up their signatures again, and reattach any PST files attached to their previous profile.

Click the bar chart icon in the MigrationWiz dashboard to receive an email containing all the project migration statistics. 

Related Topics

• Authentication Options using Graph API
• Exchange Online Advanced Options using Graph API