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In this article by, Ian Waters, David Greve, and Loryan Strant, the authors of the book, Microsoft Office 365: Exchange Online Implementation and Migration – Second Edition, so far, we have prepared you for purchasing and beginning to use Office 365. However, a key factor yet to be completed is to migrate mailbox content from your existing mail system.

We will discuss the various options available for performing a migration to Exchange Online and what needs to be done to prepare. This will cover the following topics:

  • Overview of a simple migration
  • Available migration options
  • Differences between source platforms
  • The migration process
  • Preparing your environment for migration

(For more resources related to this topic, see here.)

What is a simple migration?

When an organization looks to migrate mail in a single direction to Exchange Online, it is called a simple migration due to the fact that it is one way.

Organizations looking to retain on-premises Exchange Server functionality as well as utilize Exchange Online would choose a hybrid environment over a simple migration. A hybrid environment is a mixture of both the environments, which is more complex to implement and maintain than a simple migration.

Migration options

There are really only five main mail platform types used by organizations that wish to migrate to Exchange Online:

  • POP e-mail systems
  • IMAP e-mail systems
  • Hosted Exchange Server
  • Gmail or Google apps
  • Exchange Server 2003 or 2007

Based on these platforms we have created several scenarios which are reflective of common customer environments and situations.

POP e-mail

Many small businesses currently utilize POP e-mail provided by their domain name or website host. These are the simplest of migrations as the mailbox content is migrated by relying on the PST file import functionality in Outlook. Users simply need to import their existing PST file into the new Exchange Online mailbox.

IMAP

Some organizations may be utilizing IMAP either from a hosted service provider or on an on-premises server (such as Novell GroupWise). These mail systems can be imported natively by using the migration wizard within the Exchange Online Control Panel. It is important to note that IMAP only contains mail objects and folders (not calendars, contacts, tasks, or any other Outlook-based items as these are stored in PST files).

Hosted Exchange or Gmail

For organizations that have already made a move to cloud services and are using email from either a hosted Exchange Server provider or Gmail (aka Google Apps), they are better off utilizing third party cloud-based migration systems. An example of this is www.migrationwiz.com which allows for mailbox content to be moved from the original mailbox directly into the new Exchange Online mailbox.

Exchange Server 2003 and 2007

It is quite common to find organizations still running Exchange Server 2003 or 2007 either as a standalone solution or as part of Small Business Server 2003 or 2008.

Effectively, all that is required is the enabling of RPC over HTTP for any of the versions. However, this can prove to be challenging as the functionality was not native to Exchange Server/SBS 2003.

In Exchange Server 2007 / SBS 2008, however, there are more complexities around the provisioning of the actual certificates and utilization of the Autodiscover functionality.

The actual migration is performed by running the migration wizard within the Exchange Online Control Panel.

Staged migration

A staged migration allows you to choose which mailboxes get migrated to Exchange Online and move at your own pace. During this process, however, users of both Exchange Server on-premises and Exchange Online are in separate environments. As a result, these users will not have access to a shared Global Address List or Free/Busy information.

During the migration, all emails that are routed via the on-premises Exchange Server are also retained locally, which provides for rollback if required.

Cutover migration

A cutover migration simply begins the process of migrating all mailboxes from your on-premises Exchange Server to Exchange Online in a single step.

Migration option comparison

For simple digestion of the preceding scenarios, we have broken down the differences between the options into the following table and listed requirements for each:

Migration type / Requirements

PST Migration

IMAP

3rd Party Tool

Exchange Staged

Exchange Cutover

Server access

No

No

Possibly

Yes

Yes

Directory Synchronization

No

No

No

Yes

No

Define your own migration schedule

Yes

Yes

Yes

Yes

No

SSL certificate purchase

No

No

Possibly

Yes

Yes

PC access to migrate content

Yes

Yes

No

No

No

The migration process – in a nutshell

The steps involved in the actual migration process will differ depending on the option chosen.

Effectively, they will follow the same basic pattern:

  • Creating user accounts
  • Activating Exchange Online mailboxes
  • Migrating mailbox content

Generally, the Mail eXchange (MX) record is cut over after the completion of a successful mailbox migration. However, some administrators prefer to do this beforehand to ensure that no new mail items are left behind.

However, the key to a successful migration is not the actual mailbox content migration itself, but the planning and preparation.

Planning for migration

Several key factors must be addressed when planning the migration to Exchange Online to ensure it is done successfully. These are both technical factors as well as human factors.

Technical considerations

There are numerous technical considerations which must be taken into account when planning for a migration. Some of the more common questions are as follows:

  • Which of the previous example scenarios mirrors yours?
  • Have users been informed of the change?
  • How much data can you send through your Internet link to Exchange Online (meaning how many gigabytes of mail can be uploaded)?
  • Does your monthly Internet download allowance cater for the mailboxes being downloaded back into the Outlook .OST file for each user?
  • Do you plan to start users on Exchange Online with their full mailbox or just a portion of recent content?
  • Do you have access to all desktops so you can configure the new account in Outlook?
  • How many computers will you have to re-configure, and do you have the resources to do them all in the timeframe?

Asking questions such as these will help determine your migration plan.

For example, if you have 80 users, each with mailboxes of 5 GB, then it is not likely that you will be able to transfer 400 GB of data in a single weekend. This is especially important as Exchange Online only supports mailbox transfer speeds of 500 MB per hour (higher speeds can be achieved by raising a support request before commencing the migration). Therefore, you would most likely go for a staged migration approach (if using Exchange Server) or alternatively a third party solution such as www.migrationwiz.com which allows multiple mailbox copy passes.

People considerations

Another key element of any migration plan is change management and a communication plan with a view to ensure that the end user experience is not a negative one.

It is important to notify the users of any changes to their day-to-day operations that may impact their productivity as any disruption could further delay the migration or leave a sour taste in their mouth.

Part of the change management is to inform the users about the migration procedure at a high level so that they are made to feel part of the process.

There will also be an element of having to re-configure the desktops and mobile devices. So the more comprehensive your change management and communications, the more you will be able to empower the users to do the work themselves. However, this can also be simplified by utilizing solutions such as https://www.bittitan.com/products/deploymentpro/about (from the same company that makes MigrationWiz) to automate the desktop configuration process.

Preparing your environment for migration

Before beginning the migration process it is important to ensure that your environment has been prepared and that all requirements have been met.

Due to the varying requirements and processes, we have broken these down between types of migrations.

PST-based migrations are not documented as they are merely a file export/import procedure which requires little preparation. You may want to document a procedure which states where the PST files are stored and how they are named, and even list the PST file passwords if password protection is required.

IMAP

In order for Exchange Online to access your IMAP server/service, it must be accessible via the IMAP protocol from the Internet – which is generally the case.

It is important that the users be created via the Office 365 administrative interface, either individually or in bulk.

You also need to prepare a listing of the existing IMAP mailboxes in CSV format which is imported into the Exchange Online Control Panel. This CSV maps the IMAP credentials (e-mail address, usernames, and passwords) to the Exchange Online mailbox.

Hosted Exchange/Gmail

When migrating to Exchange Online from a hosted Exchange or Gmail environment, you will generally have less access to the environment and as such less preparation work can be done.

The process will be similar to that of IMAP whereby users are created in Office 365, followed by you working through the process of the third party provider to get access to the existing mail system and have the migration provider (for example, MigrationWiz) move the content directly.

On-Premises Exchange 2003 or later

A requirement of preparing to migrate to Exchange Online from Exchange Server 2003 or later is to ensure that the server can be reached using the RPC over HTTPS (Outlook Anywhere) method on port 443.

You must have a valid SSL certificate installed from a trusted root Certificate Authority. Self-signed SSL certificates issued by your server will not work as they are not recognized by external sources as “trusted”.

To ensure that your Exchange Server is accessible by Office 365 and ready for migration, it is recommended that you test Outlook Connectivity by using the Microsoft Remote Connectivity Analyzer (https://testconnectivity.microsoft.com).

Summary

We have walked you through some of the common scenarios seen when performing a simple migration to Exchange Online.

By now your environment should be ready, and both you and your users ready to take the final step and begin migrating your emails to the cloud.

Resources for Article:

Further resources on this subject:

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