Email Migration

Customers have used Quest® solutions to migrate over 68 million Exchange and Office 365 mailboxes.

That's a vast sea of migration experience, so we asked our customers to share their advice with one simple request:

"Tell us about your greatest lesson learned related to your email migration."

Here's what they had to say.

Careful planning is critical to success

Because email is a vital lifeline for nearly every organization today, careful planning of your email migration project is essential. While getting from one platform to another is the main objective, it's not your only goal. If your project is to be considered a success, you also need to take proactive steps to minimize disruption, loss of productivity and revenue impact along the way, whether you're undertaking an Office 365 migration or an Exchange migration.

Accordingly, customers who've been in the migration trenches advise taking the time to make a detailed pre-migration assessment of the current environment. Since every organization is different, there is no definitive checklist to use, but do your level best to leave no stone unturned.

For starters, you need to know exactly what users, mailboxes, distribution lists, groups, public folders and data stores you have. Pay special attention to potential challenges, such as large attachments, public folders, archives such as Enterprise Vault, and local offline PST files scattered throughout the organization. You also need to review your current policies and procedures for handling these items and work with your colleagues across the business to determine whether updates are in order.

Of course, you'll also want to assess other constraints, such as migration timeline mandates and available bandwidth. Determine whether there is any flexibility concerning dates or budget for infrastructure improvements that could speed the migration. Every minute you invest in planning will help ensure a successful, worry-free migration with no surprises.

Minimize the impact of the migration on your users

However, our customers hasten to point out that there is more to pre-migration planning than just the technical details; it's also critical to consider how the migration will impact your business and operations. Ideally, your migration will go so smoothly that your internal customers won't even know it happened.

Many of the lessons in this e-book detail specific ways to minimize the impact of your email migration on users. Here, let's focus just on logistics: scheduling and testing.

Be sure to schedule your migrations to minimize the impact to the users in your organization. In particular, migrate users who work together simultaneously, and carefully time the migrations to minimize impact on each group. For example, you might avoid migrating the Finance department near the end of a quarter.

Before you start any migration, carefully test both the move-forward plan and the back-out plan. Thorough testing might seem like overkill, but rest assured you will uncover problems that you wouldn't want to face once the actual migrations begin. Despite your best efforts, you might have overlooked a dependency, connectivity may be lost during a migration, or a scheduling miscommunication could result in a group of users being migrated before they are ready.

Also be sure to run one — or several — pilot migrations to validate your approach. Your goal is to test the procedures you have developed and discover gaps and challenges that could cause disruption for your users. That way, you have the opportunity to resolve them before you begin your production migrations.

Automation is critical to success

The best way to minimize the impact on users is to make your migration as quick and accurate as possible. Automation increases the likelihood of success. Once you test your migration procedure for one group of users, automate those tasks to run the same way for subsequent groups. Repeating a known successful process in an automated fashion reduces the possibility of user error and speeds completion.

Automation will also make the IT team and the C-suite happy by reducing workload and costs.

Migrations are expensive, and the biggest part of that expensive is skilled IT pros. With the right automation, you can avoid making trips to each desktop to update workstations, having to create collections manually, and many other repetitive tasks, reducing the burden on those expensive resources.

In other words, automation is a win–win–win: Users get a faster and more accurate migration, costs come down, and you get your evenings and weekends back.

Migrate only what you need to migrate

There's a second key to completing your migration on time and with less effort: Migrate only data that is actually being used. For example, eliminate orphaned mailboxes, rarely accessed files and unused accounts from your migration project. In addition to a faster migration, you'll have a cleaner target environment that is more secure and easier to manage.

Start with a full assessment of your mail system and file data to determine what data is being actively used and what might be ready for deletion or archival. But to avoid disrupting business operations, be sure to report on the LDAP calls that custom applications make to Active Directory to determine which accounts are using those applications.

Also, pay particular attention to the local files of your users, such as PST files in Exchange and archives or local mail files in Notes and GroupWise. Users like these files because they enable them to get around storage quotas and retention policies. But they can become large quickly, making them prone to corruption and data loss, and you can't easily back them up because they can reside in multiple locations and users typically have them open. Plus, you can't ensure the files meet compliance regulations or include them in e-discovery efforts.

Therefore, our customers strongly recommend using an email migration tool that can discover all the local mail files on your network. Then you can analyze those files to determine what should be moved, deleted or archived, and devise a strategy to reintegrate the valuable data back into the messaging environment before, during and after the migration process.

Make the most of your bandwidth

Most migrations involve a very high level of data transfer, so bandwidth is almost always a concern. The more effectively you use the bandwidth you have, the faster your migration is going to proceed, and the less impact it will have on production processes competing for bandwidth.

To preserve bandwidth, our customers recommend reducing the amount of data being migrated. We've already explained the importance of careful pre-migration cleanup to reduce the volume of data being migrated, but there is more you can do. Filtering data by date or size can enable you to move large amounts of data that is being rarely accessed in an archive solution. Also consider migrating the most important data first and the rest later. For example, you might choose to start by migrating only the last 30 days of data so you can get users over to their target systems in a very short period of time. After that batch of data is migrated, you can migrate the older data at a much slower pace to use less bandwidth.

Another strategy our customers have found useful is to schedule tasks to run during non-business hours when the WAN is experiencing little use. Some of them also recommend deploying migration agents that move the data closer to the servers where the data resides, since this will reduce the hops the data needs to take to its destination.

Plan for coexistence

Even with effective automation and the most careful pre-migration cleanup, most migrations do not happen overnight, or even over a weekend. In fact, many take weeks or months. During that time, it's critical that users can continue to communicate and collaborate effectively, no matter which users and resources have been migrated. Providing things like a unified GAL and the ability to send emails and schedule appointments during a migration will dramatically reduce user disruption, productivity losses and downtime, all of which can significantly impact the bottom line. Moreover, it reduces the chances of a negative first impression of the new environment, which could lead to resistance and lack of adoption.

Coexistence can mean different things to different organizations. Some make heavy use of free/busy data; others barely use it. Some rely heavily on calendaring, while others are only concerned about a complete directory of users. As a result, it is critical to work with stakeholders to develop a coherent picture of what's important in your organization and help everyone understand the importance of an effective coexistence strategy.

Achieving full coexistence is particularly challenging if you are migrating from a non- Microsoft platform. Many of these systems treat and store calendars differently than Microsoft solutions. Therefore, proper planning and the right tools are particularly critical for those migrations.

Make sure you can preserve users' Outlook profiles

No matter how quickly and accurately you migrate their email data, users who rely on Microsoft Outlook will not consider the migration a success unless you preserve their Outlook profiles as well. The profile includes things like cached email addresses and contacts, user shortcuts, and custom rules, all of which users need to maximize their productivity after the migration. If you fail to preserve their profiles, they are likely to resist adoption of the target mail system and flood your helpdesk with complaints.

However, updating Outlook profiles can be a challenge. Manually visiting each desktop to help users update their profiles is tedious and time-consuming, and would be almost impossible in a large migration. Some tools help point a user's profile to the new target system, but they do not always do so in a timely manner that brings over the settings that users care about. Be sure the solution you choose can be deployed from a network share and will update the profiles seamlessly, preserving all the settings, rules, cached information, shortcuts and other items for each user.

Be sure you can recover from problems during the migration.

The last lesson our customers say they learned is one of the most important: Even with the best planning, things can go wrong. You absolutely must be prepared for times when you need to back users out of a migration event and recover to the state they were in before they were migrated.

For example, if you accidentally put a user in the wrong migration group, overlooked an important dependency or experienced a network error that prevented a migration task from completing correctly, you need to restore back to the working state as quickly as possible.

Therefore, make sure the migration solution you choose enables you to quickly and easily roll back any changes made to the environment at any step of the migration process. Remember that users work with their source mailboxes until the mailbox is switched and the client profile is updated on the user workstation; then they start using their target mailboxes. Rollback involves switching a user back to the source mailbox and undoing the changes and updates made to the Outlook profile so that the source mailbox works exactly as it did before the migration. Effective rollback capabilities are critical to minimizing migration risk and business disruption.


Any good painter will tell you that 90 percent of the job is in the preparation. Customers who have been through migrations report much the same thing: Taking the time to do the work up front to minimize the impact on users is critical to success. Their top lessons learned include the importance of making a careful assessment of your existing environment, performing pilot migrations, automating tasks to improve speed and accuracy, excluding data that does not need to be migrated, planning for coexistence, preserving users' Outlook profiles, and ensuring you can quickly roll back any errant changes.

And, as painters also know, having the right tools can make all the difference. Ever try painting a room with just a small paintbrush instead of a roller, or trying to cut in high windows without scaffolding? You can do it, but the results won't be nearly as good and the job will take a lot more time and effort. Similarly, quality migration tools pay for themselves by minimizing the impact of the migration on the business and saving valuable IT staff time.

Quest migration solutions can help you achieve your goals. But don't take our word for it. TechValidate's independent research shows that the majority of Quest email migration customers realize return on investment in less than six months, and nearly 80 percent completed their migration on schedule or faster. To learn more about Quest migration solutions, please visit

About Quest

At Quest, our purpose is to solve complex problems with simple solutions. We accomplish this with a philosophy focused on great products, great service and an overall goal of being simple to do business with. Our vision is to deliver technology that eliminates the need to choose between efficiency and effectiveness, which means you and your organization can spend less time on IT administration and more time on business innovation.