1. BitTitan Help Center
  2. Perform a Migration
  3. Microsoft 365 Migrations
  4. Microsoft Exchange Online/Office 365 Mailbox Migrations

Microsoft 365 to (Hosted and On-Premises) Exchange (2013+) Migration Guide

This is the complete onboarding task flow for migrating mailboxes from Microsoft 365 to Hosted Exchange or On-Premises Exchange, version 2013+.

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.

Prerequisites

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

  • Exchange Web Services (EWS) must be enabled for the mailboxes in the Exchange Online tenant and the Hosted/On-Premise Exchange environment for this migration type.

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 MigrationWiz Licenses.

To use your license by following the next steps:

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

Purchase licenses by following the steps below:

  1. Sign in to your BitTitan account. 
  2. In the top navigation bar, click Purchase.
  3. Click the Select button and choose User Migration Bundle licenses.
  4. Enter the number of licenses you want to purchase. Click Buy Now.
  5. Enter a Billing address if applicable.
  6. Click Next.
  7. Review the Order Summary and enter a payment method.
  8. Click Place Your Order.

Limitations

  • App password usage, MFA/2FA, and ADFS are not supported for the migration admin account/service account being used by this endpoint.
  • The maximum file size for migration through MigrationWiz varies by migration type and environment, but may never exceed 60GB.

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.

Which items are migrated?
  • Inbox
  • Folders
  • Email
  • Contacts
  • Calendars
  • Tasks
  • Journals
  • Notes
  • Post (when the destination is Exchange or Microsoft 365)
  • Server-Side mailbox rules
  • Automatic Replies (Out of Office Messages for Exchange 2013 and 2016 only)

    Important

    It is recommended that only Automatic Replies be migrated in the last migration pass for the user. 
  • Personal Folder and Calendar Permissions (Exchange 2013 and 2016 only)
Which items are not migrated?
Never Migrated
  • Safe Sender/Block Lists
  • Calendar acceptance status emails

Groups

  • Notebooks
  • For Group documents: anything not in a document library (See SharePoint)

For additional features and limitations please visit MigrationWiz: Migrated and Not Migrated Items.

Prepare the Source Environment

Modern Authentication Requirements

The steps listed in the Required Permission for Performing M365 Mailbox and Archive Migrations article apply to both the source and destination tenant when they are Exchange Online, in regards to Exchange Web Services (EWS) in the mailbox and archive mailbox. Use a Global Administrator for the configuration steps.

Please review the documentation before preparing the source.

Create an Administrator Account

Create an administrator account in Microsoft 365 to be used for migration or use the global admin account for the tenant. The administrator account must have full access to the user mailboxes, have the required API Permissions, or be granted impersonation rights.

We recommend adding the necessary API permissions to the Modern Authentication app you are using for your O365 mailbox or archive mailbox endpoint, to do so, follow the steps outlined in this guide. This is the suggested method by BitTitan.

However, you can still use the BitTitan impersonation approach but consider that this method will be deprecated soon since Microsoft is phasing out RBAC Application Impersonation in Exchange Online.

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 Users.
  5. Click Continue.

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

Disable Throttling Against the Admin Account

The Exchange Server has very low throttling policy limits. We recommend disabling the throttling limits during the migration. This is only relevant if throttling policies are enabled in the Exchange environment. If you are creating or applying a throttling policy on Exchange, you will need to use delegation for this endpoint.

There are two options for this process. Choose which one works for you, and then expand the relevant set of instructions below. 

Option 1 Option 2

Disable throttling against only the migrating account (if not using impersonation). This way, the admin account can migrate at a faster rate because it is not subjected to any throttling.

Use this option if you are not using impersonation during the migration, but instead using delegation. If migrating using admin credentials, it is only necessary to disable throttling against the admin account, rather than all users. If migrating mailboxes using administrative credentials at the Source, but not using impersonation, we recommend disabling throttling limits on this administrative account to improve the speed of migration.

We recommend you Set Up an Exchange Administrator Account and disable policy enforcement for this account.

Read Message rate limits and throttling before you execute the scripts below.

Admin Account: Exchange 2010

To disable all throttling parameters for an admin account called "MigrationWiz":

  1. On a computer that hosts the Microsoft Exchange Management Shell, open the Microsoft Exchange Management Shell.
  2. Type the following command and press Enter.
    New-ThrottlingPolicy MigrationWizPolicy
  3. Type the following command and press Enter.
    Set-ThrottlingPolicy MigrationWizPolicy -RCAMaxConcurrency $null -RCAPercentTimeInAD $null -RCAPercentTimeInCAS $null -RCAPercentTimeInMailboxRPC $null -EWSMaxConcurrency $null -EWSPercentTimeInAD $null -EWSPercentTimeInCAS $null -EWSPercentTimeInMailboxRPC $null -EWSMaxSubscriptions $null -EWSFastSearchTimeoutInSeconds $null -EWSFindCountLimit $null -CPAMaxConcurrency $null -CPAPercentTimeInCAS $null -CPAPercentTimeInMailboxRPC $null -CPUStartPercent $null
  4. Type the following command and press Enter.
    Set-Mailbox "MigrationWiz" -ThrottlingPolicy MigrationWizPolicy
Admin Account: Exchange 2013+

To disable all throttling parameters for an admin account called "MigrationWiz":

  1. Open the Exchange Management Shell.
  2. Type the following command and press Enter.

    New-ThrottlingPolicy MigrationWizPolicy

  3. Type the following command and press Enter.

    Set-ThrottlingPolicy MigrationWizPolicy -RCAMaxConcurrency Unlimited -EWSMaxConcurrency Unlimited -EWSMaxSubscriptions Unlimited -CPAMaxConcurrency Unlimited -EwsCutoffBalance Unlimited -EwsMaxBurst Unlimited -EwsRechargeRate Unlimited

  4. Type the following command and press Enter.

    Set-Mailbox "MigrationWiz" -ThrottlingPolicy MigrationWizPolicy

Option 2: Disable throttling against all user accounts (if migrating using an admin account and using impersonation). This way the admin account can migrate at a faster rate because it impersonates user accounts, which are not subjected to throttling.

If migrating mailboxes using administrative credentials at the Source, and using impersonation, disabling throttling limits on all mailboxes will improve the speed of migration, but it is a security risk. The throttling limits are working together to protect an Exchange server from being overwhelmed by accepting and delivering messages.

Read Message rate limits and throttling before you execute the scripts below.

All Mailboxes: Exchange 2010

To disable all throttling parameters for all mailboxes:

  1. On a computer that hosts the Microsoft Exchange Management Shell, open the Microsoft Exchange Management Shell.
  2. Type the following command and press Enter.
    New-ThrottlingPolicy MigrationWizPolicy
  3. Type the following command and press Enter. 
    Set-ThrottlingPolicy MigrationWizPolicy -RCAMaxConcurrency $null -RCAPercentTimeInAD $null -RCAPercentTimeInCAS $null -RCAPercentTimeInMailboxRPC $null -EWSMaxConcurrency $null -EWSPercentTimeInAD $null -EWSPercentTimeInCAS $null -EWSPercentTimeInMailboxRPC $null -EWSMaxSubscriptions $null -EWSFastSearchTimeoutInSeconds $null -EWSFindCountLimit $null -CPAMaxConcurrency $null -CPAPercentTimeInCAS $null -CPAPercentTimeInMailboxRPC $null -CPUStartPercent $null
  4. Type the following command and press Enter.
    Get-Mailbox -ResultSize Unlimited| Set-Mailbox -ThrottlingPolicy MigrationWizPolicy

The steps above will remove throttling policies against all user accounts at your Source. You still need to enable impersonation within your MigrationWiz project, so that the admin account can impersonate the user accounts during migrations, and so that the migrations use the bandwidth available to the individual user accounts, rather than just the bandwidth available to the admin account. Follow the directions in the Help Center article Impersonation and Delegation to enable this.

All Mailboxes: Exchange 2013+

To disable all throttling parameters for all mailboxes:

  1. Open the Exchange Management Shell.
  2. Type the following command and press Enter.

    New-ThrottlingPolicy MigrationWizPolicy

  3. Type the following command and press Enter.

    Set-ThrottlingPolicy MigrationWizPolicy -RCAMaxConcurrency Unlimited -EWSMaxConcurrency Unlimited -EWSMaxSubscriptions Unlimited -CPAMaxConcurrency Unlimited -EwsCutoffBalance Unlimited -EwsMaxBurst Unlimited -EwsRechargeRate Unlimited

  4. Enter the following command and press Enter. 

    Get-Mailbox | Set-Mailbox -ThrottlingPolicy MigrationWizPolicy

The steps above will remove throttling policies against all user accounts at your Destination. You still need to enable impersonation within your MigrationWiz project, so that the admin account can impersonate the user accounts during migrations, and so that the migrations use the bandwidth available to the individual user accounts, rather than just the bandwidth available to the admin account. 

Prepare the Destination Environment

Set up the User Accounts

You can use the CSV acquired in the previous step as an easy reference point for creating these accounts. 

Create Admin Account

Create an admin account for migration that has full access permissions to all mailboxes. Any user account that is a part of the domain administrator, schema administrator, or enterprise administrator groups will not have any administrative rights to mailboxes, no matter how many permissions are granted. A security default of Exchange Server is to explicitly deny any user that is a member of these groups. This is why we recommend creating a new user account specific for migration.

  1. Open the Exchange Admin Console.
  2. Click New and select User Mailbox.
  3. Click New User.
  4. Enter "MigrationWiz" as the Display name.
  5. Enter "MigrationWiz" as the Name.
  6. Enter "MigrationWiz" as the User logon name.
  7. Enter the service account password. 
  8. Select Save.

To grant the account access, perform the following steps while in the Exchange Server machine. The command needs to be applied each time a new mailbox is created since permissions are set directly on each mailbox. The administrative account will not have access until the permissions are applied.

  1. Open the Exchange Management Shell.
  2. Enter the following command:
    Get-Mailbox -ResultSize Unlimited | Add-MailboxPermission -AccessRights FullAccess -User MigrationWizChange the -User account to match the name of the admin account that was set up for migration. This username is the Administrative Username that needs to be entered under project source or destination settings, within MigrationWiz, when check marking the box labeled: Use Administrative Login.

Optional: Large Messages

If you want to be able to migrate messages with attachments larger than 10MB, the following limits need to be increased:

Increase Message Size Limits

This is a two-step process. The reason for this is that if the message size limits of Exchange are increased, the IIS limits will also have to be increased to allow increased payloads. Other non-standard settings can also cause size restrictions for the IIS or EWS connections, but we are unable to troubleshoot or identify specific environment restrictions outside of these settings.

To display current message size limits:

  1. Open the Exchange Management Shell.
  2. Enter the following commands:

Get-TransportConfig | Format-List -Property MaxReceiveSize, MaxSendSize
Get-SendConnector | Format-List -Property Identity, MaxMessageSize
Get-ReceiveConnector | Format-List -Property Identity, MaxMessageSize
Get-MailBox | Format-List -Property PrimarySmtpAddress, MaxSendSize, MaxReceiveSize

To increase message size limits on the Exchange Server:

  1. Open the Exchange Management Shell.
  2. Enter the following commands:

Set-TransportConfig -MaxReceiveSize 150MB -MaxSendSize 150MB
Get-SendConnector | Set-SendConnector -MaxMessageSize 150MB
Get-ReceiveConnector | Set-ReceiveConnector -MaxMessageSize 150MB
Get-Mailbox | Set-Mailbox -MaxSendSize 150MB -MaxReceiveSize 150MB

Increase IIS Limits to Allow Accepting Payloads

Three limits should be increased in IIS:

  • maxRequestLength
  • maxAllowedContentLength
  • maxReceivedMessageSize

Follow these steps to increase the Exchange message size limits on your client access server:

  1. Open Windows Explorer.
  2. Navigate to %ExchangeInstallPath%FrontEnd\HttpProxy\ews\.
  3. Open the file Web.Config in a text editor, such as Notepad.
  4. Find the XML tag starting with each change.
  5. Change the existing value to maxRequestLength="200000" -- this occurs in one place on the Web.Config file.
  6. Change the existing values to maxAllowedContentLength="200000000" -- this occurs in one place on the Web.Config file.
  7. Change the existing values to maxReceivedMessageSize="200000000" -- this entry occurs up to 12 times. This needs to be changed for each Authentication method.
    For example:
    <httpsTransport maxReceivedMessageSize="200000000" authenticationScheme="Anonymous" maxBufferSize="81920" transferMode="Streamed" />
    <httpsTransport maxReceivedMessageSize="200000000" authenticationScheme="Basic" maxBufferSize="81920" transferMode="Streamed" />
    etc.
  8. If you are running IIS7 and Windows 2008, it may be necessary to increase WCF settings.
  9. Save the file.
  10. IIS Reset is not needed, web.config changes are picked up by the next connection.

Follow these steps to increase the Exchange message size limits on your mailbox server:

  1. Open Windows Explorer.
  2. Navigate to %ExchangeInstallPath%ClientAccess\exchweb\ews\.
  3. Open the file Web.Config in a text editor, such as Notepad.
  4. Find the XML tag starting with each change.
  5. Change the existing value to maxRequestLength="200000" -- this occurs in one place on the Web.Config file.
  6. Change the existing values to maxAllowedContentLength="200000000" -- this occurs in one place on the Web.Config file.
  7. Change the existing values to maxReceivedMessageSize="200000000" -- this entry occurs up to 12 times. This needs to be changed for each Authentication method.
  8. If you are running IIS7 and Windows 2008, it may be necessary to increase WCF settings.
  9. Save the file.
  10. IIS Reset is not needed, web.config changes are picked up by the next connection.
Increase Maximum Accepted Content Length

You may increase the maximum accepted content length by following these directions:

  1. Open Windows Explorer.
  2. Navigate to C:\Program Files\Microsoft\Exchange Server\ClientAccess\exchweb\ews.
  3. Open the file Web.Config in a text editor such as Notepad.
  4. Go to the end of the file.
  5. Insert or edit the following XML code before the </configuration> tag:
    <system.webServer>
    <security>
    <requestFiltering>
    <requestLimits maxAllowedContentLength="104857600" />
    </requestFiltering>
    </security>
    </system.webServer>

If XML code is already present in the Web.Config file, then edit it to match what is shown above.

Web.Config before changes Web.Config after changes
<configuration>
<system.web>
...
...
</system.web>
</configuration>
Increase Maximum Received Message Size

If you are running IIS7 and Windows 2008, you may need to increase WCF settings:

  1. Open Windows Explorer.
  2. Navigate to C:\Program Files\Microsoft\Exchange Server\ClientAccess\exchweb\ews.
  3. Open the file Web.Config in a text editor like Notepad.
  4. Find all XML tags starting with maxReceivedMessageSize=.
  5. Change existing values to maxReceivedMessageSize="104857600".
  6. Save the file.
  7. Open a Command Prompt (cmd.exe).
  8. Type: cd %windir%\system32\inetsrv.
  9. Type: appcmd.exe set config "Default Web Site/ews" -section:requestFiltering -requestLimits.maxAllowedContentLength:104857600.
  10. Run: iisreset.

MigrationWiz Steps

Create a Mailbox Migration Project

For mailbox migrations, use administrative credentials to access mailboxes. In most migration scenarios, the admin account needs to have full access rights to the Source mailboxes.

Mailbox Migration Settings: Every setting on the project is applied to all mailboxes associated with that project. For settings that are represented as checkboxes, only selected settings are applied to the project. Not selecting a checkbox does not disable a selected setting inherited from the project.

  1. Click the Go to My Projects button.
  2. Click the Create Project button.
  3. Select Mailbox migration type.
  4. Click Next Step.
  5. Enter a Project name and select a Customer.
  6. Click Next Step.

Endpoints

The steps for this section outline how to create the endpoints in MigrationWiz.

If you are selecting an existing endpoint, keep in mind that only ten endpoints will show in the drop-down. If you have more than ten, you may need to search. 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.

Client Secret for Microsoft 365 Endpoints

For all Microsoft 365 Endpoints mailbox migrations (including archive migrations), MigrationWiz adds the Client Secret field, which is not always mandatory. It will depend on the permissions of the user account that performs the migration. Please review the following information before the creation of your M365 endpoints.

Create a Source Endpoint

  1. Click New.
  2. Name the endpoint.
  3. Select type Office 365.
  4. Provide credentials. Click the Provide Credentials radio button, and enter the admin account credentials for the account that was set up under the “Prepare the Destination Environment” section of this guide.
  5. Click Add.
  6. Complete the Application (client) ID, the Directory (tenant) ID, and the Client Secret fields. Otherwise, you cannot save your project.

    Source Settings.png

  7. Click Next Step.

Create a Destination Endpoint

  1. Click New.
  2. Name the endpoint.
  3. Select type Exchange Server 2003+.
  4. Enter the OWA URL.
  5. Provide credentials: Click the Provide Credentials radio button, and enter the admin account credentials for the account that was set up under the “Prepare the Destination Environment” section of this guide.
  6. Click Add.
  7. Click Next Step.
  8. Click Save and Go to Summary.

Once the information has been provided for the source endpoint, and the customer selects Save and Go to Summary, MigrationWiz performs an endpoint validation check.

This validation tests the administrator credentials entered into the project and the Modern Authentication setup only. If there is an issue, the screen redirects to the endpoint and provides an error message or flyout that can be selected for more information regarding the error.

Common Errors when Configuring Your Endpoint

For more information review the AADSTS700016, AADSTS90002, and ADDSTS50126 issues on the Common Errors Using Modern Authentication page.

Add Users

Add the user accounts that will be migrated to the project. This may be done in several ways, depending on the size of the project. Steps for each option are in the accordion below, simply click to show the option you select and follow the guidance there.

Small Migrations

For small migrations, it is easy to add users one at a time using Quick Add. The steps for this are below. 

Larger Migrations

For larger migrations, we recommend either using the Autodiscover or Bulk Add option.

Quick Add

This option allows you to add items one at a time. To do so, you only have to provide an email address if you entered administrative credentials when setting up the project. If you did not, enter the following user information:

  • An email address
  • Login name
  • Password
  • Mailbox status
Bulk Add

Bulk Add uses a CSV containing the source and destination email addresses for the users to add the users to the project. If migrating only a specific group from a tenant, we recommend using the Bulk Add option.

MigrationWiz allows you to bulk import mailboxes into the system.

To import one or more mailboxes:

  1. Sign in to your MigrationWiz account.
  2. Select the Project for which you want to perform the bulk import.
  3. Click Add.
  4. Click Bulk Add.
  5. Follow the instructions on the page.

    Important

    After adding new users to the Bulk Add Items page, make sure to select the radio button All newly detected mailboxes will be migrated as shown below before clicking on the green Save button)

    New Bulk Add Requirement.png

Autodiscover

​Autodiscover process within MigrationWiz can be used to discover items from the Source environment so that they can be imported into your projects. This can then be edited in the project to remove users not being migrated. All users are added with the source and destination email addresses set to match the source email.

This can be changed by using the Change Domain Name button at the top of the project page. If the usernames are changing during the migration, we recommend using the Bulk Add option.

There are a few requirements for this to work:

  • The Source has to be Exchange 2007 or later, or Microsoft 365, or G Suite. If you are using Autodiscover from G Suite, all G Suite domains must be added to the list of domains in the Endpoint.
  • The endpoint on the Source needs to use admin credentials.
  • For mailbox migration projects, the admin account that is specified within the Source endpoint needs to have a mailbox associated with it.
  • The admin mailbox must be listed in the public Global Address List (GAL).
  • The migration project type needs to be a Mailbox migration. For the exact steps to be followed during your migration, refer to the relevant Migration Guide. All Migration Guides can be found on the Help Center site.

One additional item to note here is that there is no way to restrict the IP addresses that the connection will come from.  This means that the steps outlined in our IP Lockdown guide will not apply here.  If your environment requires that any IP addresses be whitelisted, it is recommended that items be added to your project using one of the other available options.

Autodiscover of items will not work while using Modern Authentication

Autodiscovery exposes the following items:

  • For mailbox migration, autodiscovery will list all mailboxes at the Source.

Steps to Run Autodiscover

  1. Navigate to the project you want to import users into.

  2. Ensure that you have created an endpoint for the source project.

  3. Once in the project, on the top navigation bar, click on the Add drop-down, then select Autodiscover Items. This will begin the Autodiscover process.

  4. Once discovered, click on the Import button, to import the items into your MigrationWiz project.

Advanced Options

Support Tab

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.

Important

Keep in mind that the ModernAuthClientSecretExport and the ModernAuthClientSecretImport support options are text-masked.

Warning

You cannot update the default Advanced Options, in case you try to modify or add new ones the following message arises.
Duplicate Support Option.png

Source/Destination Tab

Set to use impersonation at the Destination. Checkmark the Use Impersonation at Destination box if you choose to use Impersonation instead of Delegation. If you choose to use Delegation, this box needs to remain unchecked.

For large projects only: If this is a large migration project, increase the value for Maximum concurrent migrations, under the Performance section, e.g., 200. This can be set to a high number if impersonation is set to be used at the Source, and your Destination Exchange server has plenty of resources available.

Run Verify Credentials

You may verify the credentials of items in MigrationWiz without migrating data or consuming any licenses.

  1. Open the Project containing 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.

Once complete, the results of the verification will be shown in the Status section.​

Notify Users

Notify users that a migration is occurring. Send an email to all users telling them the time and date of the migration.

Run Migration

Pre-Stage pass

  1. Select the users you wish to migrate.
  2. Click the Start button from the top.
  3. Select Pre-Stage Migration.
  4. Uncheck the box named Automatic Replies (This option will be removed from the Pre-Stage pass at a later date)
  5. Under the Migration Scheduling section, from the drop-down list, select 90 days ago.
  6. Click Start Migration.

MX Record Cutover

Change over MX records on the DNS provider's portal. Also, include the AutoDiscover (CName) setting.

Send an email to end users to let them know what to expect for their Outlook profile reconfiguration. If using DeploymentPro, refer to Sample email to send to users before their Outlook profile is reconfigured for some sample text and screenshots that can be included in this email.

Full (Delta) pass

  1. Select the users.
  2. Click the Start button from the top.
  3. Select Full Migration. 

    Important

    It is recommended that only Automatic Replies be migrated in the last migration pass for the user. 
  4. Click Start Migration.

Run Retry Errors

Look through the user list and click any red "failed migration" errors. Review the information and act accordingly.

If problems persist, contact Support.

Post-Migration

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

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