Prerequisite Step 3 - Provision Microsoft 365 mail users

Note

This is the third of four steps required before migrating Google mail to Microsoft 365. Complete steps 1 and 2 before you continue.

• Prerequisite Step 1 - Create a subdomain in Google Workspace to route mail to Microsoft 365 and
• Prerequisite Step 2 - Create a subdomain to route mail to Google Workspace

Important

As an IT administrator, you must have the "Recipient Management" role group assigned before starting the migration process. For more information, see Permissions in Exchange Online.

In Prerequisite Step 3, you create mail user accounts and proxy email addresses for all users you want to migrate from Google Workspace to Microsoft 365.

Check out our video on Google mail migration prerequisites:

External mail contacts

In Exchange Online organizations, there are two types of external contacts: mail users and mail contacts.

A mail contact provides information about an external user. Mail contacts don't contain sign in credentials for your Microsoft 365 organization and aren't used for accessing resources.

A mail user entry contains an external email address, contact information, and sign-in credentials for your Microsoft 365 organization. Mail user accounts can access resources and services. You can manage mail users in the Exchange admin center or via PowerShell.

For more detailed information on mail contacts and mail users, see Recipients in Exchange Online.

Provision mail users with Exchange admin center

Sign into the Microsoft 365 admin centerwith your administrator credentials.

1. Select Show all and then select Exchange.
2. Expand Recipients, select Contacts and select Add a mail user.
3. On the Set up the basic information page, enter the information of the user you want to migrate.
4. Fill out the remaining information and select Next.
5. Select Create. Repeat this process for each user you want to migrate.

Required	Setting	Example
No	First name	"Alex"
No	Last name	"Wilber"
Yes	Display name	"Alex Wilber"
No	External email address	Enter the email that uses the Google Workspace mail routing subdomain. alexw@gws.tailspintoysco.com
Yes	Alias	Same as User ID and External email address. "alexw"
Yes	User ID and Domain	Enter the alias used for External email address. "alexw" In Domain, select the primary domain in the drop down menu. "tailspintoysco.com". Final result is alexw@tailspintoysco.com.
Yes	Password
Yes	Confirm password

Add proxy email addresses to mail users

Now you need to add a proxy email address for each user to route their mail to the Microsoft 365 subdomain.

1. Select Mailboxes and select a user from the list.
2. A panel with details of the user appears. Under Email addresses, select Manage email address types.
3. Select + Add email address type.
4. Verify STMP option is selected.
5. Enter the user alias in the Email address field and select the Microsoft 365 routing subdomain you created. Select OK and then Save.
6. Repeat the process for any other users.

Other ways to provision mail users

Provision mail users with PowerShell

To manage mail users using PowerShell in Exchange Online, you can use the following cmdlets:

• Get-User
• Set-User
• Get-MailUser
• New-MailUser
• Remove-MailUser
• Set-MailUser

Note

When creating mail users using PowerShell, you may experience throttling limitations. PowerShell commands may also take a few minutes to become visible due to batch processing.

Example of mail user formatting in PowerShell

Use the following command in Exchange Online PowerShell to create a mail user for Alex Wilber:

• Name/display name: Alex Wilber
• Alias: alexw
• External email address: alexw@tailspintoysco.com
• Sign-in name: alexw@contoso.onmicrosoft.com
• You're prompted to enter the password.

New-MailUser -Name "Alex Wilber" -Alias alexw -ExternalEmailAddress alexw@tailspintoysco.com -FirstName Alex -LastName Wilber -MicrosoftOnlineServicesID alexw@contoso.onmicrosoft.com -Password (Read-Host "Enter password" -AsSecureString)

For detailed syntax and parameter information, see New-MailUser.

Provision mail users with Microsoft Entra ID (advanced scenario)

1. See Deploy Microsoft 365 Directory Synchronization in Microsoft Azure for an overview.

2. Follow the setup instructions in Set up directory synchronization for Microsoft 365.

3. Set up an Exchange server in your on-premises environment to manage users and enable mail for them.

4. Check How and when to decommission your on-premises Exchange servers in a hybrid deployment and Manage mail users for more information.

5. If you've created mail users in Microsoft 365, disable Microsoft Entra Connect so the migration process can convert them into mailboxes. See Turn off directory synchronization for Microsoft 365 for details.

   • The primary address or User ID must be provisioned using the primary domain.
   • If a user's primary address is in a different domain, make sure the proxy email address in the primary domain.
   • Each user's ExternalEmailAddress should point to their Google Workspace routing subdomain.
   • Users should also have a proxy address that routes to their Microsoft 365 routing subdomain.

6. Disable the Default MRM Policy and Archive policies for users until the migration is complete. Keeping these policies enabled during migration may cause some messages to appear "missing" during content verification.

7. After configuring your Google Workspace environment, you can complete your migration in the Exchange admin center or Exchange Online PowerShell.

Next steps

Prerequisite Step 4 - Verify Google migration administrator role assignments