How Small Organizations Can Migrate Exchange Mailboxes to Office 365?

 En Exchange Online, Office 365

Office 365 has become one of the essential requirements for organizations. It is helping small as well as mid-level organizations to have an enterprise-level email communication system with minimal investment on infrastructure. Also, Office 365 subscription is far more convenient and economical than an on-premises Exchange Server deployment.

However, migrating from Exchange to Office 365 is a bit complicated as there are many factors involved in it, such as the number of mailboxes you want to migrate, internet speed, sizes of the mailboxes, etc. In accordance with these factors, there are different ways to migrate on-premises Exchange mailboxes to Office 365.

In this article, we’ll guide you through different methods to migrate Exchange mailboxes to Office 365. But, before starting the migration process, make sure you go through the limits as well as the best practices for Exchange Online to get the performance and behavior you expect after migration.

Limits of Exchange Online

Exchange Online has a few limits for a variety of service areas like mailbox storage limit, address book limits, etc.

  • Address List Limits

There is a permissible limit to the number of address lists that you can create. This limit includes the default address lists in Exchange Online, such as Contacts and Groups.

  • Mailbox Storage Limits

The mailbox storage limit is determined by the mailbox type and user’s subscription plan. An administrator can reduce the maximum mailbox sizes globally or per user. Usually, the maximum mailbox size limit is up to 50 GB. However, the mailbox size limit also changes based on the type of mailboxes.

  • Mailbox Folder Limits

The primary goal of mailbox folder limit is to limit the number of mailbox items per folder, folders per mailbox, or public folders per Exchange Online organization. For example, the limit for the maximum number of messages per mailbox folder is 1 million in Office 365 Business Essentials.

  • Receiving Limits

The receiving limits apply to both messages received from the Internet and from on-premises servers. If the receiving limits exceed, that mailbox user will get a warning message. For the Office 365 Business Essentials plan, the receiving limit is 3,600 messages per hour.

Methods to Migrate Exchange Mailboxes to Office 365

There are three types of migration that can be performed from an on-premises Exchange Server. Below, we have mentioned these methods in detail:

  1. Cutover Migration or Express Migration

If you’re using Exchange 2003, 2007, 2010, or 2013 and the mailboxes are less than 2000, then you can perform the cutover migration. However, Microsoft suggests migrating 150 users or less at a time because it’ll take a lot of time to migrate 2000 mailboxes at once. You can implement the cutover migration from the Exchange Admin Center.

Express migration, also known as Minimal Hybrid, can be performed if you’re running at least Exchange 2010, 2013, or Exchange 2016 Server on-premises. Express migration takes a couple of weeks or less to migrate Exchange mailboxes to Office 365. You can perform the Express Migration by going to the Office 365 Admin Center.

  1. Staged Migration

The staged migration method is not suitable for organizations that run Exchange 2010 or 2013. It is viable for organizations that are using Exchange 2003 or 2007. When you perform migration of user mailboxes from a source email system to Office 365 over time, it is known as Staged migration.

It can only be implemented if an organization have more than 2000 mailboxes because for fewer mailboxes you can use Cutover or Express migration.

  1. Hybrid Migration

If you’re using Exchange 2010 or 2013, then you should give first preference to Hybrid migration instead of Cutover or Staged migration. With Hybrid deployment, you can maintain both on-premises and online mailboxes for your organization. The greatest benefit of Hybrid deployment is that it provides an integrated environment of both on-premises Exchange and Office 365.

The Hybrid migration method allows mailboxes to be off-boarded from Office 365 to Exchange on-premises without using third-party tools. You can perform Hybrid migration if you have Exchange 2010 or 2013, and more than 150-200 mailboxes.

The only drawback of using Hybrid migration is that it relies on directory synchronization. And for some reason, if the organization cannot implement directory synchronization, then it might have to use a third-party solution for the migration.

Kernel Migrator for Exchange – A complete tool for Office 365 migrations

Kernel Migrator for Exchange is a powerful tool that is specially designed to migrate Exchange mailboxes to Office 365. It is enriched with some great features, some of which include:

  • Migrate between on-premises Exchange Server and Exchange Online
  • 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/archive mailboxes and public folders
  • Advanced filters to migrate specific mailboxes and folders
  • Migrates limits/permissions of mailboxes & public folders
  • Updates Outlook profiles and migrates rules
  • Offers co-existence between Exchange & Office 365 after migration
  • Option to schedule migrations and set blackout hours


KME Express – For Office 365 data migration without Outlook

Kernel Migrator for Exchange – Express is a light-weight utility for the migration of data from mailboxes and public folders between different types of Exchange environments – on-premises, hosted, and cloud. It can be used to migrate mailboxes from Exchange to Office 365 without the need of MS Outlook program. Apart from Exchange migration, it offers some great features for Office 365 migration, such as:

  • Migration of on-premises Exchange mailboxes to Office 365 mailboxes
  • Migrate cloud-based Office 365 mailboxes to any version of Exchange Server
  • Migrate single/multiple mailboxes according to your requirements
  • Migrate “N” number of mailboxes using CSV file
  • Supports on-premises, hosted, and cloud Exchange deployments.


The Express edition of Kernel Exchange Migrator gives you full freedom to migrate Exchange mailboxes to any platform whether it’s on-premises or cloud. This software is suitable for those who want to migrate Exchange mailboxes to Office 365 without any hassle. A demo version of this tool can be obtained on request.


Exchange to Office 365 migration can be tricky and hectic if you don’t use the right method for migration. So, before starting the migration, make sure which method you want to use depending on your requirements and size of mailboxes. Also, after finalizing a technique, try a test migration first, and then perform the actual migration. However, many Exchange administrators prefer third-party Exchange migration tools because of the ease of migration.

0 0 vote
Article Rating
Entradas Recientes
Notificar a
Inline Feedbacks
View all comments
Would love your thoughts, please comment.x
almacenamiento, storage, máquinas virtuales, cifrado, seguridad, capacidad, iops, gib, discos, premium, ssd, alto rendimiento, capacidad, escalabilidad, hddlicencias Open, Open Value, Open Value Subscription, Office 365 y CSP

Al continuar utilizando nuestro sitio web, usted acepta el uso de cookies. Más información

Uso de cookies

Este sitio web utiliza cookies para que usted tenga la mejor experiencia de usuario. Si continúa navegando está dando su consentimiento para la aceptación de las mencionadas cookies y la aceptación de nuestra POLÍTICA DE COOKIES, pinche el enlace para mayor información. Además puede consultar nuestro AVISO LEGAL y nuestra página de POLÍTICA DE PRIVACIDAD.