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Summary: Microsoft Office 365 provides a seamless platform for organizations to transition to a subscription-based email system, offering versatile methods for migrating existing email data. Administrators can transfer mailboxes, and different migration methods are available for Exchange, PST files, and IMAP-enabled systems. End users can also independently import their emails. Kernel Exchange Suite and Kernel Exchange Migrator are recommended for efficient and comprehensive email migration to Office 365, catering to various requirements.

Microsoft Office 365 stands out as a highly valuable platform for organizations, offering a subscription-based email system that eliminates the need for any upfront infrastructure investment. When transitioning to this cloud-based solution, there are several versatile methods available for migrating existing email data to Office 365 mailboxes. Moreover, Office 365 empowers end users to effortlessly import their emails, contacts, and other essential mailbox information directly into their Office 365 mailboxes.

Administrators can seamlessly transfer mailboxes from Exchange Server or other IMAP-enabled email systems, simplifying the transition process. In this section, we will explore the process of migrating multiple email accounts to Office 365. However, it’s essential to address certain limitations associated with the manual approach before diving into the migration process.

  • Need to add passwords by resetting or assigning it manually for every user
  • Chances of migrating duplicate items are there
  • Processes are lengthy and thus require patience
  • Data loss or incomplete migration conditions may arise
  • Have to check for supported email server versions before migration

Factors considered before executing the migration from emails accounts to Microsoft 365

  • The volume of data for the migration
  • Number of items for migration
  • Current email system and version
  • The time required for the migration process

Now, let’s see how to migrate emails from different systems to Office 365.

Migrating Exchange Mailboxes to Office 365

Three distinct migration methods are available when transitioning from an Exchange Server. In the following section, we will elaborate on each of these methods.

  1. Cutover Migration or Express Migration: If you are currently using Exchange versions such as 2013, 2010, 2007, or 2003 and have fewer than 2000 mailboxes to migrate, the recommended method is Cutover Migration. However, it’s important to note that Microsoft suggests migrating no more than 150 users at a time due to the significant time required for migrating a large batch of 2000 mailboxes simultaneously. You can initiate the Cutover Migration from the Exchange admin center.

    Another migration option, known as Express Migration or Minimal Hybrid, is available for those who have on-premises Exchange servers like 2013, 2010, or Exchange 2016. Express Migration is a relatively quicker process, typically taking a couple of weeks or less to migrate Exchange mailboxes to Office 365. It’s worth mentioning that Express Migration is a multi-step procedure because it is more comprehensive and can be time-consuming. The steps involved in Express Migration include:

    • Verifying that you own the domain
    • Starting the Express migration process
    • Running directory synchronization to create users in Office 365
    • Providing Office 365 licenses to your users
    • Migrating user mailbox data
    • Updating DNS records

    You can perform the Express Migration from Office 365 Admin Center.

  2. Migrate Mailboxes with Staged Migration: The Staged Migration method is best suited for organizations utilizing Exchange 2003 or 2007; however, it is not recommended for those running Exchange 2010 or 2013. This approach becomes particularly advantageous for organizations with over 2000 mailboxes. Nevertheless, prior to embarking on a staged migration, it is imperative to familiarize yourself with essential insights and considerations.
  3. Migrate Using Hybrid Environment: If you’re currently operating on Exchange 2013 or 2010, prioritizing a Hybrid deployment is strongly recommended over cutover or staged migrations. The Hybrid approach allows you to seamlessly manage both on-premises and cloud-based mailboxes for your organization, offering the most robust user experience despite its complexity.
    One noteworthy advantage of the Hybrid migration method is its ability to provide a unified environment for both on-premises Exchange and Office 365. Additionally, it stands alone as the sole migration technique that enables mailbox off-boarding from Office 365 to on-premises Exchange without the need for third-party tools. If your goal is to migrate a substantial number of mailboxes, typically exceeding 150-200, then perform Hybrid deployment is the way to go.
    However, it’s essential to acknowledge that the Hybrid Configuration relies heavily on directory synchronization. If, for any reason, your organization cannot implement directory synchronization, alternative third-party solutions or manual migration methods may become necessary.
Migrating PST Files to Office 365 Using Import Service

Office 365 offers a valuable import service designed to assist administrators in seamlessly migrating multiple PST files to Office 365 mailboxes. If you’re looking to streamline the process of migrating PST files for your organization, the Office 365 Import service provides you with two efficient methods to choose from. You can either upload the PST files directly to Office 365, or alternatively, send the PST files securely through a physical drive to Microsoft. These two distinct approaches are defined as:

  • Performing a Network Upload is a straightforward process that can be broken down into several key steps. To begin, you’ll need to install Azure AzCopy. Next, you’ll upload your PST files to Office 365. Then, you’ll create a PST import mapping file using a CSV format. After that, you’ll establish a PST import job within Office 365. Finally, you’ll apply data filtering as needed and initiate the import job. For a more in-depth understanding of how the Network upload method operates, you can delve into its detailed workings.
  • The Drive Shipping Method is a more extensive process, requiring you to send your PST files to Microsoft and subsequently await the Microsoft team’s upload of these files to your Office 365 account. To perform Drive Shipping method, you must obtain a secure storage key and the PST Import tool, both provided by Microsoft.
Migrate Emails from IMAP Enabled Email System

You can migrate IMAP mailboxes to Office 365 using PowerShell commands commands or the IMAP Service available in the Office 365 Admin Center.

With the IMAP (Internet Message Access Protocol) service, you can seamlessly transfer user emails from platforms such as Gmail, Outlook, Exchange, and other email systems that facilitate IMAP migration. However, it’s important to note that IMAP migration exclusively caters to the migration of items contained within the user’s mailbox or other mail folders. Regrettably, it does not extend its capabilities to migrating contacts, calendar entries, or tasks.

Utilizing PowerShell commands can be perceived as intricate due to the involvement of numerous shell cmdlets and the necessity for a solid grasp of shell commands. Furthermore, the steps encompassed by this approach can be quite challenging, encompassing tasks such as establishing an IMAP connection to Office 365, generating a CSV file for migration batches, and creating an IMAP migration endpoint, among others. Nevertheless, harnessing the power of PowerShell commands can streamline the migration process, allowing for the smooth transfer of all data contained within IMAP mailboxes to Office 365.

Ask end users to import their own emails

Users have the flexibility to independently import their emails, contacts, and various mailbox items into Office 365. To initiate this migration process, it’s imperative to ensure that your email account is IMAP-enabled. Additionally, Microsoft Outlook must be installed on your system. Once you’ve confirmed IMAP activation in your email account, please proceed with the following steps:

  • Go to the Outlook app and add your IMAP account to your Outlook.
  • Once the account is added, it will be shown in Outlook.
  • Now, copy your IMAP messages to your desktop.
  • The messages/emails will be saved in the PST format.
  • After saving the messages on the desktop, you can copy that file to Office 365 mailbox.

Once the PST file is copied to Office 365 mailbox, you can remove the IMAP email account from your Outlook profile.

An all-in-one solution to migrate emails from multiple sources

Say goodbye to the tedious process of manually migrating emails from various sources to Office 365. Instead, streamline your email migration with the powerful and user-friendly Kernel Exchange Suite. This cutting-edge solution is purpose-built for seamless migrations from live Exchange/Office 365 to Office 365/Exchange. In addition to data migration, it offers the flexibility to export mailboxes from EDB, PST, and OST files directly to Office 365 or live Exchange. This feature-rich tool boasts a host of capabilities, including:

  • Convert EDB, OST files to PST format
  • Migrate offline data files to live Exchange/Office 365
  • Migration of user/shared mailboxes and public folders to Exchange environment
  • Migrate Office 365/Exchange mailboxes to Outlook, Exchange, and Office 365
  • Advanced filters to migrate specific mailbox and folders
  • Support for all Exchange/Outlook versions and Office 365 plans
A complete solution for Exchange/Office 365 migrations

Escape the complexities associated with manual mailbox migrations from Exchange to Office 365 by employing a streamlined approach. Embrace the efficiency of Kernel Migrator for Exchange, a powerful solution designed specifically for Exchange/Office 365 migrations. This exceptional Exchange Migration tool boasts a plethora of outstanding features, including:

  • Migrate between two different Active Directory forests
  • Pre-migration analyzer to get an idea of the duration of migration
  • Migration of Exchange mailboxes to live Exchange and Office 365
  • Migration of user/shared mailboxes and public folders
  • Advanced filters to migrate specific data from mailboxes/public folders


Various organizations employ a variety of email servers to facilitate their daily operations. As the shift towards Office 365 gained momentum, many were eager to harness the benefits it offered. However, the challenge arose when contemplating the migration of multiple email systems from diverse platforms, making manual migration impractical. Consequently, individuals began seeking comprehensive solutions to streamline this process. Kernel Exchange Suite and Kernel Exchange Migrator emerge as the perfect tools, adeptly addressing the complete spectrum of requirements for seamless mailbox and email migration to Office 365.