IMAP to Microsoft 365 Migration Guide

​​​​​​​​Introduction

This is the complete onboarding task flow for migrating mailboxes from IMAP systems to Microsoft 365. 

App passwords are not supported for the Microsoft 365 endpoint. 

Due to API limitations, IMAP migrations will only migrate mail items and we can only migrate mail items that are stored on the IMAP server. Verify that a copy of the mail remains on the server. If there is no mail on the IMAP server and it's stored in a local PST, use the PST migration process. If the data is stored in a local Outlook OST file (Outlook 2013 and Outlook 2016), export the mailbox to a PST and use the PST migration process.

There are some tools and resources that will make the migration easier.

First migration?

We’ve created a guide on scoping, planning, and managing the migration process for your use. If this is your first migration, we recommend reading this guide carefully.

 

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.

MigrationWiz supports the capability to share migration projects across a Workgroup. When the Project Sharing feature is turned on, all Agents besides those who are Inactive can view all migrations projects. 

We are not able to support migrations with two-factor or multifactor authentication. 

The maximum file size for migration through MigrationWiz varies by migration type and environment, but may never exceed 60GB.

Prerequisites

There are many different versions of IMAP mail systems available. For this reason, we recommend running a trial migration on one or more mailboxes prior to the actual full migration project. Once the trial migration completes, check on the folder structure at the Destination to ensure that the directory structure is as desired. 

To run a trial migration, follow these steps:

  1. Sign in to your MigrationWiz account.
  2. Click on your migration project. If you haven't created a project, create a project (following the steps laid out in the Create a Mailbox Migration Project below) and add a user to that project.
  3. Select the user for whom you wish to perform the trial migration.
  4. Click on Start.
  5. From the drop-down list, click on  Trial Migration .
  6. Click on Start Trial Migration.

This guide includes a folder mapping under the MigrationWiz Steps section, which will ensure that folders are mapped to the root label on the Destination mailboxes, rather than under inbox/label name.

Prepare the Source Environment

  1. Test connectivity to the IMAP server through our connectivity test tool. Fill in the form and click the Test button.
  2. Export user list to a CSV file.
    • Administrator accounts with at least read rights can export a user list.
    • If you do not have an administrator account, you will need to ask your IMAP host to provide you with a complete user list, in CSV file format.
    • This CSV file will be used to bulk-add users into your MigrationWiz mailbox project.

Prepare the Destination Environment

Create the admin account

  1. Create a user in Office 365
  2. Connect to Exchange Online by using remote PowerShell
  3. Type the following command, and then press Enter:
    Get-Mailbox -ResultSize unlimited -Filter {(RecipientTypeDetails -eq 'UserMailbox') -and (Alias -ne 'Admin')} | Add-MailboxPermission -User AdministratorAccount@mydomain.com -AccessRights fullaccess -InheritanceType all

After you perform these steps, the specified user will be able to access all user mailboxes in Microsoft 365. The user will be able to view the contents of the mailboxes from either Outlook or Outlook Web App.

Set up accounts in Microsoft 365

  1. Set up accounts on Microsoft 365 and assign licenses. These can be created in several ways:

Prepare the tenant to send & receive large items

We do not impose any limit on item/attachment sizes. However, it is possible for large items/attachments to fail to migrate because of external factors. Microsoft provides more information on message size limits

  1. What is the maximum attachment size allowed by the Destination system? 
    • Most email systems impose size limits. For example, if the Destination system has a 30MB limit, any item/attachment larger than 30MB will fail to migrate.
  2. What is the connection timeout for the Source and Destination system? 
    • ​​For security reasons, most email systems close opened connections after a predetermined amount of time. For example, if the Destination system only has 512Kbps of network bandwidth and closes connections after 30 seconds, we may be unable to transfer large items/attachments before the connection is closed.

MigrationWiz will automatically make multiple attempts to migrate large items.

Upon completion of a migration, you may resubmit it in error retry mode to try to migrate failed items. This is always free of charge.


Authentication Requirements

Exchange Online EWS Authentication Requirements

The two options listed below apply to both the source and/or destination tenant when they are Exchange Online, in regards to Exchange Web Services (EWS) in mailbox, archive mailbox, and public folder projects. Select the option you wish to use for either your source or destination tenant. Use a Global Administrator for the configuration steps.

Important: Failure to perform the steps for one of the two required options for your Microsoft 365 endpoints, can result in failed jobs with 401 errors like the following in your project: Http POST request to 'autodiscover-s.outlook.com' failed - 401 Unauthorized


Regardless of the option selected, the administrator account being used for the project needs to be excluded from any MFA/2FA policies or Conditional Access policies that can block access for the administrator account. This requirement does not apply to the items or users being migrated in the project.

Of the two options available, the more recommended is the Modern Authentication option, as it is more secure. Configuring Modern Authentication to work with MigrationWiz and Exchange Online will be the default method by end of December 2022 due to Microsoft discontinuing support for Basic Authentication in Exchange Online. The following Microsoft documentation outlines this change in more detail. Should you have additional questions on how this change may impact your tenant, please contact Microsoft to assist with providing that information: Deprecation of Basic authentication in Exchange Online

Regardless of the option selected, the Azure Security Defaults must also be disabled in the tenant. (This is often enabled by default for all new Exchange Online tenants and there is no workaround for this requirement). For steps on where to enable/disable the Azure Security Defaults, see Enabling security defaults in the following Microsoft documentation. To disable, set Enable Security defaults to No: Security defaults in Azure AD

Basic Authentication Modern Authentication

BitTitan currently uses Basic Authentication by default for mailbox, archive mailbox, and public Folder migrations with Exchange or Exchange Online endpoints. The steps below do not apply to GCC or GCC High tenants. If electing to enable Basic Authentication for a GCC or GCC High tenant, a request will need to be manually submitted to Microsoft. The steps outlined below can also be found (with screenshots) here: Basic Authentication Deprecation in Exchange Online – September 2022 Update

Steps for enabling Basic Authentication in the tenant for Exchange Web Services

 

  1. Ensure you are signed into the O365 Admin Center as a Global Administrator.
  2. Click on the Help & Support icon (this is often a green icon on the lower right-hand corner of the O365 Admin Center page). This will open the Self-Help system. 

  3. In the search box under How can we help?, enter Diag: Enable Basic Auth in EXO

  4. Under Run diagnostics, click on Run Tests
  5. Once the diagnostic test completes, you will be given a dropdown list named Protocol to Opt Out

  6. From the dropdown list, select Exchange Web Services (EWS) and check the box for acknowledging the changes to be made.

  7. Click on Update Settings.

  8. After the settings have been implemented, it could take up to an hour before the settings take full effect in the tenant.

MSPComplete Steps

Create Customer

  1. Click the Add button in the top navigation bar
  2. Click the Add Customer button on the All Customers page
  3. In the left navigation pane, select the appropriate workgroup and then click All Customers.
  4. Click Add Customer.
  5. Enter the new customer’s information in the Add Customer form. Primary Email Domain and Company Name are required. The rest are optional.
  6. Click Save.
  7. Repeat steps 1 through 4 for each customer you want to add. 

Purchase licenses

We recommend that you purchase the User Migration Bundle license for this migration scenario. User Migration Bundle licenses allow multiple types of migrations to be performed with a single license. They also allow DeploymentPro to be used to configure Outlook email profiles. For questions on licensing, visit MigrationWiz Licenses

To purchase licenses:

  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.

Apply licenses

  1. Select the correct workgroup on the top of the left navigation pane. This is the workgroup that the customer and migration project were created under. Your account must be part of the workgroup if the project was not created under your account.
  2. On the left navigation pane, click Customers.
  3. Click the customer that employs the user to whom you want to apply a User Migration Bundle license.
  4. Click the Users tab at the top of the page.
  5. Check the box to the left of the email for the user(s) to whom you want to apply a license.
  6. Click the Apply User Migration Bundle License button at the top of the page. It is recommended that users be added to the Customer page with the vanity domain. Then have the User Migration Bundle Licenses applied, before editing to show the .onmicrosoft domain, if the .onmicrosoft domain will be used for the migration.
  7. If there is at least one unassigned User Migration Bundle license available for each selected user, click Confirm. Important: If there are no User Migration Bundle licenses currently available to be assigned and your role in the workgroup is Manager or higher, the form that appears provides all the necessary information and will walk you through the steps of purchasing User Migration Bundle licenses.

 

MigrationWiz Steps

Create a Mailbox Migration project

  1. Click the Go to My Projects button.
  2. Click the Create Project button.
  3. Click on the type of project that you wish to create. For this migration:
    • Mailbox: Mailbox projects are used to migrate the contents of the primary user mailbox from the previous environment to the new environment. Most mailbox migrations can migrate email, calendars, and contacts.

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. 

  1. Click Next Step.
  2. Enter a Project name and select a Customer.
  3. Click Next Step.

Endpoints

Endpoints are now created through MigrationWiz, rather than through MSPComplete. 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.

You may either use existing endpoints, or create new ones. 

To create a new source endpoint:

  1. Click Endpoints
  2. Click Add Endpoint
  3. Select IMAP
  4. The server name should follow the format: imap.example.com

  5. Enter server port. As a general rule, the server port will be either 143 or 993 (if using SSL).

  6. If you are using SSL, add a checkmark next to Use SSL.

To create a new destination endpoint:

  1. Click Endpoints
  2. Click Add Endpoint
  3. Enter endpoint name
  4. For endpoint type, select Office 365
  5. Fill in the required fields.

Add Users

Add the user accounts that will be migrated to the project. MigrationWiz allows you to bulk import mailboxes into the system.

Use the Bulk Add option, and import from the CSV file that you prepared under the Prepare the Source section of this guide. 

Admin Account

If you have an admin account on the Source IMAP system, the format will be as follows.
However, most IMAP systems do not support administrative credentials. 

The following systems support IMAP: 

  • G Suite supports OAuth authentication.
  • Some versions of Novell GroupWise support Trusted Key authentication. Click here to learn more.
  • Some versions of Exchange IMAP support admin authentication. Click here to learn more.

Format: 

  • Source Email: SMTP email address.
  • Source Login Name: Consists of two combined names: the user name of the person whose email is being migrated, and the user name of the mailbox admin account. For example, for Exchange IMAP: Domain/Admin_UserName/User_UserName. The proper formats can be found here.
  • Source Password: Enter the administrator's password.

If administrative login is not available

  1. Request credentials from each user.
  2. Reset mailboxes to use the same password (this will lock users out).
  3. Have us automatically request credentials from end users. Click here to learn more.

To request credentials from users: 

Enter the Source Email addresses in the Source Email column, and checkmark the I don't know the login name and password for the Source mailboxes box. Users will then be requested to provide their credentials during the migration process.

For the Destination, you only need to enter the Destination email address of each user.

Bulk Add

To import one or more mailboxes once you have gathered the necessary credentials: 

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

Add Advanced Options

Under Source / Destination:

  • Set to use impersonation at Destination. Checkmark the Use impersonation at Destination box. 

Optional but recommended, under Support/Support options:

  • Add folder mapping: FolderMapping="^INBOX/->"
    • This will map folders to the root label on the Destination mailboxes, rather than under inbox/label name. 

Run Verify Credentials

  1. Open the Project containing items you wish to validate.
  2. Select the items you wish to validate.
  3. Click on 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 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. Under the Migration Scheduling section, from the drop-down list, select 90 days ago
  5. Click Start Migration.

MX Record Cutover

Change over MX records on the DNS provider's portal.

Also, include the AutoDiscover (CName) setting.

 

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

Unexpected Extra Arguments

If errors are listed in the MigrationWiz dashboard with the following error message: "Unexpected extra arguments to Examine Context: FolderNameWithQuote", then follow the steps below to add the support option flag AllowQuoteInFolder=1 at the item level, and run retry errors. 

Steps

  1. Click the Edit Item icon to the right of the item that you wish to edit
  2. Under the Support section, enter the support option: AllowQuoteInFolder=1
  3. Click Save Item
  4. Select the line item in your MigrationWiz dashboard
  5. Click Start
  6. Retry Errors

Outlook Configuration

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

Request Statistics

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

 

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