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Different Ways to Migrate Multiple Email Accounts to Office 365 Suite

Published By Mohit Jha
Anuraag Singh
Approved By Anuraag Singh
Published On May 20th, 2024

To migrate over to Office 365 there could be many different ways depending on your current environment. Therefore, in this article, we will list various ways to migrate multiple email accounts to Office 365. Furthermore, using this, Office 365 administrators can easily import emails, contacts, calendars, tasks, and notes, and drive data to their mailboxes. Microsoft 365 (formerly known as Office 365) is one of the most commonly used collaborative web suites designed for personal and business use. It provides innovative applications such as Office app, web service, intelligent cloud service, and top-class security, you can achieve more and reach your goal faster.

When we talk about migrating data between platforms, it becomes a tedious task to execute. Let’s discuss the initial step towards it to make it an easy approach.

Before proceeding with the techniques to migrate multiple accounts mailbox to Office 365, there are some limitations that need to be considered first.

  • Require you to reset the password of every user
  • Good changes in migrating duplicate data
  • Complex process and requires high technical knowledge
  • The chances of data loss and corruption are quite high.

Factors that need to be taken into consideration before migrating multiple email accounts to Office 365:

  • The type of items that need to be migrated
  • Quantity of data for migration
  • Existing mail environment and version
  • Downtime during migration

Manual Ways to Migrate Multiple Email Accounts to Office 365 From Google Vault

When your existing environment is Google Vault and you want to switch over to Office 365, then the only possible way is to first export all user data to PST format using eDiscovery, then import PST to Office 365.

Migrate From Outlook Email Accounts to Office 365

To perform such migration first you need to either export all Outlook user emails one-by-one or use take the backup from the configured service in .pst format. Then you can migrate the PST file to Office 365 account directly.

Migrate Multiple Exchange Email Accounts to Office 365

There are mainly three types of migration that can be done from an Exchange server. Following are the types of migration that can be done. 

  • Cutover or Express Migration

If you are using Exchange 2003, 2007, 2010, or 2013 and you have a mailbox with less than 2000 items, then Cutover Migration is the best method to follow. Microsoft recommends that you should migrate 150 users or less at a time as it can become quite time-consuming to migrate 2000 mailboxes at once. Users can implement Cutover Migration from the Exchange admin centre. Express Migration can be performed if you are running Exchange 2010, 2013, or 2016 servers on-premise. This type of migration takes a couple of weeks to migrate and it involves a couple of steps as it is a lengthy process. It involves the following: 

  1. Verifies the ownership of the domain.
  2. Express Migration process initiation.
  3. Synchronises the directory to create users.
  4. Provides licenses to users for Office 365.
  5. Migrates the mailbox data of the users. 

Express Migration can be done from the Office 365 Admin Center. 

  • Staged Migration

This method is not suitable for users using Exchange 2010 or 2013. It can only prove to be useful for users who are using Exchange 2003 or 2007. It can be implemented in an organisation that has more than 2000 mailboxes. 

  • Hybrid Environment

If you use Exchange 2013 or 2010, then Hybrid deployment should be the first preference instead of cutover or staged migration. With this type of migration, you can maintain both online as well as on-premise mailboxes. Even though it is the most complicated method, it offers one of the best user experiences. It is also the only method of migration that allows migration to be off-boarded from Office 365 to Exchange on-premise without using any automated tool.

Migrating PST Files Using Import Service

Office 365 offers an import service to admins for migrating multiple PST files to Office 365 mailboxes. This service can be used by either uploading the PST files to Office 365 or mailing the PST files in a drive to Microsoft. The definitions of these two methods are given below. 

  1. Network Upload – This is easier to perform as it involves a few steps such as installing Azure AzCopy. The steps are:
    1. Uploading PST files to Office 365.
    2. Using CSV to Create PST import mapping file.
    3. Creating a PST import job.
    4. Filtering the data. 
    5. Performing the import.
  2. Drive Shipping method – It is a lengthier process that involves sending your PST files to Microsoft and then the users need to wait for the Microsoft team to send back those files to them. To perform the Drive shipping method, you are required to download a storage key that is secure and the PST import tool. 

Migration Using IMAP Enabled Email System

You can either use PowerShell Commands or Using IMAP Service in the Office 365 Admin Center. 

Using the Internet Message Access Protocol (IMAP) you can migrate user emails from various systems that support IMAP migration. Items in the users’ mailbox or other mail folders can only be migrated with the IMAP service. It does not allow the migration of contacts, calendars, and other files and folders. 

Using PowerShell is very complicated as it includes inputting various cmdlets. Various complicated steps include the following: 

  1. Connecting IMAP.
  2. Creating a CSV file for the migration.
  3. Creating IMAP endpoint. 

However, you can easily migrate the whole data of IMAP mailboxes using PowerShell. 

How can End Users Import Their Own Emails?

Users can import their emails, contacts, and mailbox items to Office 365 on their own. For this migration, users will have to make sure that their email account is IMAP enabled. Outlook should also be installed on their system. After ensuring that IMAP is enabled, you can follow the steps given below: 

  1. Go to Outlook and add your IMAP account.
  2. The account will be shown once it is added to Outlook. 
  3. Copy the IMAP messages to your desktop.
  4. These emails will be saved in the PST format. 
  5. After saving the messages, you can copy these files to the Office 365 mailbox.

You can remove IMAP email account once the PST file is copied to Office 365 mailbox.


When we talk about migrating data between platforms, it becomes a tedious task to execute, but it can performed easily by understanding the steps for migration. It is important to keep in mind the limitation that the migration process has. Users should plan their migration process thoroughly to prevent any data loss and make the entire migration process less time consuming.