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Microsoft 365 Considerations

The following considerations should be taken into account when migrating to or from Microsoft 365.

On this page:

• Authentication
• Define primary email address in user list
• Update EWS throttling settings
• Migrate to/from an Online Archive
• Increase send/receive limits
• GCC High

Authentication

When migrating multiple accounts to or from Microsoft 365, you will use Modern authentication.

• Modern Authentication (OAuth 2.0)

Define primary email address in user list

In your user list it is required you define the primary email address of each mailbox you are migrating from and to, rather than an alias.

• Identify Primary SMTP address of a Microsoft 365 mailbox

Update EWS throttling settings

Message throttling will slow down your migration and can generate errors. It is strongly recommended when migrating to Microsoft 365 that you update throttling settings through the admin center in advance of your migration.

• Update EWS throttling settings

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 Configuration 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.

   

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

   

2. Select the Exchange Admin center

   

3. Click recipients

4. Select All users

5. Click Set default message size restrictions

   

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

   

In New Exchange Admin Center

1. Select Mailboxes

2. Click Set default message size restrictions

   

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).

   

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

   

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

GCC High tenants

When migrating to or from a Microsoft GCC High tenant, change the default Exchange server name to outlook.office365.us (rather than the default outlook.office365.com which applies to commercial tenants).

Note: This is required for GCC High tenants only, and not standard GCC tenants.