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Microsoft 365 Considerations

When performing a migration of bulk users using a service account (so that you don’t need end-user passwords), you will need to assign an Application Impersonation role to your administrative account in Microsoft 365 (formerly called Office 365).

On this page:

Authentication

Assign the ApplicationImpersonation role to your migration account using the Exchange Admin Center, or use Exchange PowerShell. Impersonation allows you to migrate user accounts with the migration account’s credentials so you do not have to provide user passwords.

Requirements:

Prior to setting up ApplicationImpersonation, we recommend you confirm you’re using the primary SMTP email address of each account (including your administrative account).

  1. All mailboxes (including the admin account) must be active and licensed mailboxes in M365.
  2. All shared mailboxes must be set up as licensed mailboxes (not aliases, distribution lists or groups). After migration you may convert them to shared mailboxes and remove the license (shared mailboxes don’t require licenses).
  3. Transend can only migrate data into a primary email address, and cannot connect to an alias.

Learn how to identify the primary SMTP address of a mailbox.

Set up Impersonation in New Exchange Admin Center

We recommend creating a cloud-only service account with a licensed mailbox from Microsoft 365 Admin Portal > Users. Make sure you first Disable Multi-factor authentication for this account.

  • Create a user account (i.e. migration@domain.onmicrosoft.com) and assign ApplicationImpersonation role.
  • Use the primary SMTP email address of the migration account and user accounts to connect to M365 mailboxes.
  • The account (i.e. migration@domain.onmicrosoft.com) must be a licensed mailbox in M365.

  1. Click Roles > Admin roles in the side navigator.

  2. Click Add role group button.

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  3. Enter Role Name and Description. Click Next.

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  4. Select ApplicationImpersonation and click Next.

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  5. Add the migration account and click Next.

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  6. Click Add role group.

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  7. Add the account (i.e. migration@domain.onmicrosoft.com) and Password into Transend Migration Console on the Configuration Settings > Required page.

  8. Click Verify to validate the connection is working using EWS Impersonation.

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Setting up Impersonation with Powershell

  1. Open the Exchange Management Shell.
  2. Run the New-ManagementRoleAssignment cmdlet to add the permission to impersonate to the specified user.
  3. Change “ServiceAccount” to the account you are assigning impersonation to.

The following example shows how to configure Application Impersonation to enable an administrator account to impersonate all other users in an organization:

Example:

New-ManagementRoleAssignment –Name:impersonationAssignmentName –  Role:ApplicationImpersonation –User:serviceAccount

Debug Application Impersonation Rights

Click on Service Account Access and perform the login test for the migration account:

https://testconnectivity.microsoft.com/

Migrate to/from an Online Archive

Microsoft 365 mailboxes have an affiliated Online Archive (In-Place Archive) that you can migrate data directly into our out of. To migrate data into or out of the Online Archive, rather than the live mailbox, follow these steps in Transend Migration Console:

  1. Go to the Optional Confiuration Settings page.

  2. In the Basic Options tab, select the Migrate from Online Archive checkbox or Migrate to Online Archive checkbox, depending on your migration scenario.

  3. After the appropriate checkbox is selected, click Continue to complete configuration of your migration.

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Increase send/receive limits

You can increase the send/receive limits in Microsoft 365 to allow larger messages and attachments to migrate.

  • The default limit is set to 35 MB per message.
  • This can be increased to 150 MB (or 153600 KB).

In Classic Exchange Admin Center

To increase the default limits, follow these steps:

  1. Open the Microsoft 365 Admin Center and click Show ALL

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  2. Select the Exchange Admin center

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  3. Click recipients

  4. Select All users

  5. Click Set default message size restrictions

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  6. Set to preferred size. It is recommended to set this higher than the limit on your source email system so attachments can migrate with messages. This can be set up to the maximum limit of 153600 KB (or 150 MB) and click OK

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In New Exchange Admin Center

  1. Select Mailboxes

  2. Click Set default message size restrictions

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  3. Set to preferred size. It is recommended to set this higher than the limit on your source email system so attachments can migrate with messages. This can be set up to the maximum limit of 153600 KB (or 150 MB).

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  4. Click Save

Set Custom Option in Transend Migration Console

  1. Click Configuration Settings > Optional

  2. In the Basic Options tab, enter 150000 into the Set maximum attachment size allowed by target system option

  3. Also enter 150000 into the Set maximum messages and attachment size allowed by target system option

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  4. The items that exceed the defined limits will be detached from the migrated message and stored in a folder specified in directory defined in the Set directory for detached attachments that exceed the target system limits option.

    The message will migrate with a stub that says:

    “This attachment has been removed due to size, click here to download the attachment.”

You may define any directory path to store the detached attachments in. The default is set to:

C:\ProgramData\Transend\detached\$sourceIdentifier