How to Migrate Mailbox from On-Premise to Office 365? Multiple Solutions Explained

Published By Mohit Jha
Anuraag Singh
Approved By Anuraag Singh
Published On August 11th, 2023
Reading Time 9 Minutes Reading
Category Migration, Office 365

Are you struggling while searching for the right answer to the query i.e. “how to migrate mailbox from On-Premise to Office 365?” Don’t worry anymore! You have come to the right place. 

Here, we are going to discuss some of the best techniques to migrate On-Premise Exchange mailbox to Office 365. So, whether your current on-premises server is Exchange or Lotus Notes, we have a solution for you.

In the past few years, many organizations switched over to Office 365 suite due to its popularity and the functionalities it delivers. And, now it’s becoming common.

However, there are a large number of organizations that are still struggling to make the transition due to a lack of technical experience with Office 365. But why care, when you have us? We will tell you the exact steps you need to follow to migrate mailbox(es) from the current on-premises environment to the new Office 365 account.


The migration from traditional on-premise Exchange email systems to the rapidly expanding Microsoft Office 365 cloud has become a strategic move for numerous organizations today. This shift not only enhances business operations but also contributes to overall cost reduction. Consequently, users are swiftly migrating from On-Premise Exchange Servers and adopting Microsoft Office 365.

Microsoft 365 offers streamlined management compared to conventional desktop-based services. It also eliminates associated management complexities. Hence, in this write-up, we are covering all the possible ways to migrate On-Premise Exchange to Office 365 accounts.

These methodologies enable users to seamlessly migrate emails from On-Premise Exchange to Office 365, including all the mailbox items such as email, contacts, and calendars. 

However, manual approaches to migrating email messages to Office 365 can be intricate and time-consuming. To achieve a more direct and effortless process, users can also consider utilizing the below-mentioned tool. 

This blog effectively outlines these methodologies, empowering users to efficiently migrate their existing email messages to the Office 365 platform.

Why Do Organizations Struggle While Moving Mailboxes From On-Premise to Office 365?

Migration of legacy environment & data of multiple users without data loss requires a massive investment of resources and time. Before proceeding with data migration, users need to preplan their data, choose the right cloud platform, create users, purchase licenses, and assign roles and licenses to users.

The trouble doesn’t end here, the biggest problem is transferring mailboxes from on-premises to Office 365 for every user on the old platform.

Although there are no shortcuts, tricks, or hacks to perform an initial task, there are some techniques that can assist you in easier data migration. This technique helps the Administrator to easily migrate mailboxes between both environments without affecting the day-to-day work of your employees.

Different Ways to Migrate Mailbox from On-Premise to Office  365

During the process of migrating from an established on-premises Exchange Server environment, administrators can effortlessly export all email communications, contacts, and calendar entries from the user mailboxes. Subsequently, to effectuate mailbox migration, users have the option to execute five distinct migration methods, as elaborated below, in order to transfer email messages to Microsoft Office 365:

Below are the top 4 manual migration methods offered by Microsoft. And, the 5th is an automated solution. 

  1. Cut Over Migration
  2. Staged Migration
  3. IMAP Migration
  4. Hybrid Migration
  5. Automated Solution By SysTools

#1 Express or Cutover Migration (Migrate all mailboxes at once)

If a user is using Microsoft Exchange 2007, 2010,2007, or 2003 and there are a total of 2000 or fewer mailboxes to migrate from On-Premise to Office 365. Then the cutover migration approach becomes an ideal choice. This migration process can be executed through the Exchange Admin Center (EAC) and serves as a direct method for migrating mailboxes from On-Premise to Office 365.

Note: Using Express migration, one can migrate up to 2000 mailboxes only. However, if a user migrates 150 or fewer mailboxes, it will be more reasonable. It is because while creating and migrating 2000 users, it takes lots of time.

Cutover Migration Steps using Exchange Admin Center (EAC):

Step 1. Evaluate the required workload and strategize for a successful cutover migration.

Step 2. Now, validate ownership of the destination domain in Microsoft 365.

Step 3. Then connect your existing email system to Microsoft 365.

Step 4. Generate a cutover batch for the migration process.

Step 5. Start the migration process for the cutover batch.

Step 6. Implement measures to reduce the likelihood of email delays.

Step 7. Set up email routing to send messages directly to Microsoft 365.

Step 8. Conclude the cutover migration batch upon successful completion.

Step 9. Allocate appropriate licenses to users in Office 365.

Step 10. Complete essential post-migration tasks for a seamless transition.

#2 Staged Migration (Migrate Mailboxes in Batches)

If you are having Microsoft Exchange server 2003 or 2007 that possesses over 2,000 mailboxes, and wish to execute a batch migration. Then you have the option to consider Staged Migration. This approach is predominantly favored by medium-sized enterprises seeking to establish a lasting email presence within both an on-premises environment and Exchange Online (Office 365).

Step By Step Guide for Staged Migration Using EAC to Migrate from On-Premise to Office 365

Step 1. Prioritize and evaluate the workload for the staged migration process.

Step 2. Verify your ownership of the destination domain in Microsoft 365.

Step 3. Utilize directory synchronization to establish user accounts in Microsoft 365.

Step 4. Create a comprehensive list of user mailboxes earmarked for migration.

Step 5. Set up a seamless connection between your email system and Microsoft 365.

Step 6. Migrate your Exchange On-Premises mailboxes to the Microsoft 365 environment.

Step 7. Commence the staged migration process in manageable batches.

Step 8.  Convert on-premises mailboxes into mail-enabled users in Microsoft 365.

Step 9. Direct email flows seamlessly to Office 365 to ensure uninterrupted communication.

Step 10. Conclude the staged migration batch after successful completion. 

Step 11. Conduct thorough post-migration checks to ensure a successful transition.

#3 IMAP Migration to Migrate Mailbox from On-Premise to Office 365

Regarding IMAP Migration, it is important to note that this method exclusively facilitates the transfer of emails, excluding the migration of contacts, calendars, and other related data. Additionally, the maximum capacity for items migrated from a user’s mailbox is limited to 500,000 items.

#4 Hybrid Migration (Migrate an integrated Exchange Server and Office  365 environment)

Whenever a user wants to migrate between both on-premises and online mailboxes for the organization, simply use the hybrid migration method. It lets you migrate users and email messages to Office  365 step by step. In this method, a user is allowed to move their existing email messages to Office  365. It does not require a user to create a new mailbox. However, one can use this type of migration if and only if:

  • You are running Microsoft Exchange 2010 with more than 150 to 2,000 mailboxes.
  • You are running Microsoft Exchange 2010 and want to export mailboxes in small batches over a particular period of time.
  • You are running Microsoft Exchange 2013.

Step By Step Process for Hybrid Migration to Migrate Mailbox from Exchange On-Premise to Office 365

Step 1. Start the Hybrid migration process by creating an endpoint between the on-premises Exchange Server and Office 365.

Step 2. Then enable the proxy service, which acts as the key component of the hybrid migration. This service facilitates secure and efficient data transfer between On-Premise Exchange Servers and Microsoft Office 365 environments. Eventually ensuring data integrity throughout the migration process.

Step 3. Now, use the Exchange Admin Center (EAC) to initiate the migration of mailboxes. Use the Hybrid Migration Wizard to guide you through the process, ensuring a structured and well-organized transfer of mailbox contents.

Step 4. Once migration batches have fulfilled their purpose, proceed to delete them systematically.  

Step 5. As the migration advances, ensure a smooth transition for end-users by re-enabling Outlook Web Access.  

#5 Best Way to Migrate On-Premise Exchange Mailbox to Office 365

The previous section was all about the manual process, where an administrator needs to perform tasks one by one for each user. Above all the manual methods have their respective shortcomings and drawbacks. You can say that by using the SysTools Exchange to Office 365 Migration Software, you will be able to mitigate all the restrictions of manual approaches and can experience a hassle-free migration. 

This automated tool is quite easier to operate and offers multiple functionalities to ease the migration journey.

Benefits of Using Automated Tool Over Manual Solution

  • Offers concurrent migration feature to migrate user accounts in batches.
  • Use category and date-range filters to refine data before migration.
  • Multiple options for mapping database files with respective user accounts
  • Retry Failed and Re-Run Full option to handle migration upon power & internet connection loss
  • Provides unlimited delta passes to migrate newly arrived data to Office 365 in the next attempt.
  • Previews the live status of migration of each mailbox into respective cloud accounts.
  • Generates summary and detailed migration report for checking migrated data.

Download Now Purchase Now

Detailed Software Steps to Migrate Mailbox from On-Premise Exchange Server to Office 365

Step 1. Launch the migration utility and activate it for a demo or full version.

migrate mailbox from on-premise to Office 365

Step 2. Select the Exchnage On-Premise as the source and Office 365 platform as the destination.

Step 3. Choose the category of items to migrate from On-premise to Office 365 and set date filter.

Step 4. In the source tab, select the folder location where the database is saved and validate.

Step 5. In the destination tab, provide the details of the Office 365 platform and validate.

Step 6. Select the option for source and destination user ID mapping.

Step 7. Validate the user accounts and Click on Start Migration to migrate mailbox from On-Premise to Office 365.

Why Do We Care?

A typical data migration contains a huge amount of data from multiple user accounts. Also, migrating mailboxes manually at once would guarantee failure as it requires performing multiple steps for each user database.

Thus, keeping this requirement of users in mind, we have discussed migration methodologies to migrate email messages to Office  365. One can refer to them and choose between them according to their choice to move their existing email messages to Office  365. However, the administrator requires an automated tool to successfully migrate mailboxes from On-Premise to Office 365, especially when the number of users is more and the database is large.

Moreover, the software doesn’t impact the day-to-day work of users, the admin can perform the data migration without letting users log out of their systems.