Which is the Best Exchange Migration Strategy? Exchange Migration Tools or Custom Migration Services

Exchange Migration Tools Vs Exchange Migration Services

Deciding upon the Right Exchange Migration Strategy can be a complex decision. Should you outsource, make use of native or third party migration tools, handle migration in-house or use combination of these to achieve your migration goals?

In this article, we look at exchange/office 365 migration options, when to make the decision to outsource or attempt to migrate using internal resource. There are no clear cut boundaries for your exchange migration strategy here but we hope with our suggestions you have a clearer idea of where to head and what to do.


If time stood still, perhaps we wouldn’t.

But with organisations merging, company buyouts, strategy changes and system upgrades, your mailboxes will need to move at least every 10 years but usually far more frequently than that. Click To Tweet

It’s not long until Exchange 2010 will no longer be supported and if you are using older versions of Exchange then support will have finished a while back now. This means you take a chance with the lack of security updates and patches leaving your email system vulnerable to attack.

Your system may be up to date but due to a merger your emails need to be moved to the buyer’s email service.

You may want to move your mailbox between Office 365 tenants or migrate on or off Office 365.

You may decide to move from one hosted email provider to another as you’re not happy with your current service.

For these and other reasons migrating is a regular requirement and so below we suggest the best approach we think you should take for your email migration strategy.


Let’s start with the different types of Exchange/Office 365 Migrations available to you which vary in levels of complexity.

Cutover Migration

Normally completed over a weekend or holiday period, the entire migration is completed in one go. The benefits of this sort of migration is that it’s quick and takes less time to setup and manage but the disadvantage is that there is a finite time available for the migration, so it works better with smaller organisations with smaller amounts of data to migrate.

This method of Migration also gives you limited time to confirm the successful status of the migration before switching over and going live.

Staged Migration

Once you reach the point that you just have to much data and users to comfortably move in a weekend or holiday period then you need to be considering a staged migration. Depending on the size of the organisation a staged migration can take days’ weeks or months to transfer the required data. 

With this method huge amounts of data can be migrated in the background without affecting your users. It also gives more time to complete testing of migrated data and mailboxes can be migrated within groups. 

Depending on your migration method, connectivity may or may not be needed between the two mail systems.

Hybrid Migration

A third alternative to Cutover and Staged Migrations is a Hybrid Migration. A hybrid environment involves connectivity between on premise and cloud based email systems. The same Active Directory, Global Address List, Calendars, tasks etc. are available to your organisation across both locations. 

A Hybrid Environment provides a working environments across your on-premise and cloud systems but it also offers a method of completing a controlled migration between the two (and over time) by specifying at which site your mailboxes reside.


While still an option, the exporting of mailboxes to PST files and importing again to the new system has been superseded by more robust tools to do the job. Used by migration service providers and local IT resource alike, migration tools are the recommended method of completing a migration. Which tool you use will depend on your requirements so we touch on this area below.


For Exchange to Exchange migrations, Microsoft has provided the means to migrate but it’s not an easy task and will take a considerable amount of time to complete. This can be made even more complex if you plan to migrate Exchange 2003 and 2007 to Exchange 2016 or higher. With the mail servers not able to exist in the same forest and cross-forest not supported. You will find yourself having to migrate to Exchange 2010 or 2013 first.

If migrating to Office 365, then your life will be easier their ms exchange migration tools but you may still find your migration frustrating by how basic the tools are or how complicated the migration procedures. For example, if completing a staged migration, you may find yourself having to setup synchronisation between your on premise Active Directory and Azure AD. 

There are no filtering options with the proprietary tools, it’s all or nothing and no scheduling to kickoff your migration automatically outside office hours.

Third Party Tools

Tools like our solution migrate using Exchange Web Services allowing us to freely migrate mailbox items from source to destination without any requirement to establish connectivity and remaining totally domain independent. 

If you don’t have administrator level access you can collect the login details automatically. You can filter by email date, item type and schedule migrations. EWS migration systems don’t care what domain is pointing where to migrate a mailbox, you can sort that out later, when you’re ready to switch over.

With 3rd Party Migration Tools you can split down in to stages with historical emails (for example, a month ago to back as far as the earliest email) first, followed by a few catch up (or delta passes). Very often, items that are likely to be changed by the user (for example tasks, calendars and contacts) can be left until the very last minute, then migrated in the final pass.


As per IT Jobs Watch Statistics for Contract Jobs in UK, the median daily rate for an IT contractor with Email Migration Skills has increased by 13.33% over the 6 months to 5 August 2019 with a comparison to same period last year. Click To Tweet

[Source: https://www.itjobswatch.co.uk/contracts/uk/email%20migration.do]

Now let’s look at the size of organisations and what we feel is the best approach.

The size of your organisation has a big impact on how you approach the migration. We generally break down organisations in to 4 categories.

Micro Businesses [Staff Members: 1 to 9]

The justification of having IT staff internally just isn’t there for this size of business (unless of-course you’re running an IT based business). This means you have very little choice but to seek outside assistance with your migration be it a friend with technical knowledge or yours IT support company.

You could opt to find a specialist migration provider but at this size of organisation someone with a bit of migration experience will do. With this size of organisation, making mistakes while migrating is not the end of the world, most will be recoverable from quickly (if your careful) and with such a low number of users it won’t take too much effort to sort things out again and appease an upset team. We suggest a technically competent individual using proprietary or 3rd party tools.

Small Businesses [Staff Members: 10 to 49]

They are the next category up and with size comes more responsibility. At the lower end of this group you can still just about get away with a migration issue or two but at the other end you will definitely be in trouble. Staff member won’t see the funny side of it if your email is down or be sympathetic if they can’t do their job and their boss is jumping up and down as you just missed getting a tender to a client in time. 

With this number of users, thorough planning is required and experience with migrations is definitely a benefit. At this size you may or may not have a single IT person in-house to assist with the IT so if you have one, you need to quiz them on their experience levels and establish if you and they are comfortable handling this in-house, outsourcing of a combination of the two. 

There are options here. It may be that you outsource the actual data migration but your IT person handles the desktop and mobile device switchover on the ground, you may want to outsource everything if your IT guy is too busy or doesn’t have enough experience or they may be comfortable with doing it in house by themselves or maybe with a bit of temporary help.

Medium Size Businesses [Staff Members: 50 to 249]

You may have a small IT team or still be outsourcing your IT. You may have IT staff that have prior migration experience. Experience is a necessity at this size of organisation as an issue with your migration will be crippling and with so many users, you could be days fixing issues if something did go wrong. 

At this size of organisation, it would be worth having someone responsible for coordinating the project to make sure that everyone knows what’s going on and the whole organisation is coordinated.

In our opinion (and we are sure others may disagree), this is the category that is just getting to big to think about Migrating over a weekend using a Cutover Migration (mentioned in the previous section) without the risk of something going wrong so a cutover migration is just not a great choice when you get to this size. With this group there are lots of options and therefore decision to make.

 It’s is likely that your organisation will have complex IT solutions that will need to be considered and on the basis of this and available resource, a decision to handle the migration internally or outsourced in full or part. If uptime is critical then we would recommend outsourcing your migration although it still may just be possible to handle this in-house with the size and complexity of these size organisations.

Large Businesses [Staff Members: 250 & above]

You’re likely to have an Internal IT team of 2 plus IT people and depending on how large your organisation is, then possibly many more. Individual staff need to be tasked with the IT and project management roles. Prior experience of project management would be a big benefit together with the technical experience gained from prior migrations. 

If this is not available in house or your staff just don’t have the time, then we would recommend outsourcing rather than trying to squeeze it in with the day to day. For medium and large business (and to a lesser degree smaller businesses) email is a critical tool and without it a business can crumble so an ill-advised cost saving in a migration could come back to bite you later. 

Unless you are confident that your in-house team can cover this, we suggest you hire a migration expert that can provide custom migration services. Consider handling some roles (for example, switching user’s profiles) internally if you need to reduce cost but the core migration roles should be handled by the experts.


The larger your organisation is the bigger the justification to outsource to third party exchange migration services. Professional migration services do this every day, and with this comes migration experience, including the pitfalls that may cripple an experienced team. 

For small or large businesses, we would still recommend using a 3rd Party Email Migration Tool like ours for a cutover or staged migration or a proprietary tool if you have the extra time, experience and/or don’t need the flexibility of a 3rd party tool.

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