How does Email Archive Migration work?

Previously we covered the possible reasons to migrate your email archives. But how does email archive migration work as a process, what requirements are there for a company to make the process go smoothly, and what are the possible end states or outcomes that you can aim for?

Data migration is complex, but is also something most companies with an online presence will have to undergo at some point. Let’s go through the theory step by step and see what is needed to make your data transfer easy and efficient.

What is the process for a smooth and efficient migration?

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The process of migrating data from a source system into a new destination system needs to be carefully planned; according to Gartner, 83 % of data migrations fail outright or exceed their allotted budgets – a shortcoming that can only be overcome by advance preparation.

Planning and inspection:

The first critical step is the pre-migration planning and inspection of data to be migrated. As discussed in our blog article on the subject, there are a number of potential pitfalls facing companies looking to perform an archive migration – one of the major ones being disorganized storage, imperfectly preserved organization, and incompatible data formats.

Before a migration is to take place, the data needs to be inspected and pruned so that only relevant content is migrated. Storage complications and organization are also reviewed at this point. Other things that are key to take note of is how the handover to a new system is going to occur; archiving can continue using the old system (which maintains continuity but slows down the migration process by requiring constant checks in the old storage for new content), or it can be handed over to the new system immediately.

Data backup and migration process design:

Designing the migration process requires identifying your target solution, examining your desired end state and possibilities, and adjusting the process accordingly. There are several theoretical approaches that can be taken), but in practice only a gradual segmented migration is relevant to companies given the volumes involved. In this case, it is important to segment the company into groups and decide what data has to be migrated to the new system in what order of priority. Do certain groups need access to the new system as soon as possible? Do others need to continue working with minimal disruption to their agenda? These are things to keep in mind when planning out the migration process and laying out what will be migrated when and how.

Other major considerations are questions of storage space and configuration; in the case of transferring to Office365, for example, it is only possible to restore the original email rather than a shortcut. This causes a data set that only occupied 100 MB in the source system to suddenly require 500 MB in the target. Conversely, if the data can be deduplicated either by the migrator tool or an alternative, it may end up requiring less storage space than initially. In either case, this needs to be identified and planned for beforehand.

Once orders of priority have been set, a small subsection or a set of test data should be migrated to ensure the process and chosen tools are working as intended. If so, this test data can be discarded and the true migration performed. Before any substantial changes are made or steps taken, the existing data is backed up and preserved.

Migration process and validation:

Based on previously stated priorities, data is segmented and bookmarked. Then, ideally using a migrator tool, the data begins being transferred by segment. The migrator uses bookmarks to avoid transferring already migrated information. Depending on the tool in question, the target system and the user settings, migrated data may become available in the target system immediately or not.

Once the final segments of data have been transferred, the main portion of the migration process is complete. Now, in the case of your original solution not having been frozen, a final migration can be performed targeting any changed files – for example, emails entered into the source archive after migration had begun. Once these differences are accounted for, the process is over.

What follows is the so-called “validation” process. The data in the target system is compared either with the version in the original source system, or with the backed-up copy. The role of validation is to ascertain that the process has concluded successfully, with no errors occurring throughout.


After the validation concludes, the old system can be shut down and decommissioned to avoid incurring further operating costs or licensing fees, depending on the desired end-state of your migration process.

This is not a necessary step, and there may be situations where portions of the legacy system or even the solution in its entirety is left active to some degree.

What different end-states are possible for migrating my email archive?

There are a number of options available to companies looking to migrate their email archive into a new system. The key ones to take note of all reflect on how exactly the new system is implemented

Virtual/Partial migration

Virtual migration is offered by some migration experts and tools. In the case of a virtual migration from an older source system to a new one, the existing archive ecosystem remains in place in a reduced form and is connected to a more modern ecosystem via a connector program. While this saves costs on migrating the data, it introduces fees by nature of running two archive systems side-by-side, in addition to risking possible complications in the case of a future migration. Partial migration still maintains the existing database and storage, while reindexing the contents for access via a new UI.

Physical migration

In performing a physical email archive migration, the migrator tool is altering not only the archiving system in place but also the physical location of the database and storage; data is migrated to a new server, indexed, and integrated fully into a new archive. This option is used if, for example, your company is migrating from an on-premise solution to the Cloud, or moving from one server to another.

Removal of archive

In the case of companies that wish to dispense with their archiving solution entirely, it is possible to take mailboxes that had previously been archived and reintroduce them to Exchange (provided the user has a Microsoft 365 subscription).

Overcome any challenges to your email archive migration with contentGATE

There are options available to anyone looking to perform an email archive migration, but the first decision that has to be made is if your company will attempt the process in-house or find an experienced partner for access to expertise, tools and support.

There is an easy and simple way to overcome the complexity of the migration process – migrating with a trusted partner, who can offer years of experience and a proven migrator tool. TECH-ARROW can offer our contentGATE migrator tool, no matter if you are migrating between email servers, DMS, Microsoft 365, Microsoft Exchange, or any one of the over twenty-five most common email archive solutions on the market.

By depending on a trusted external partner to facilitate your migration, you reduce the strain on your own company and resources while ensuring a positive outcome and placing barriers against the most common mishaps that can plague less-experienced migration projects. Contact our team and receive a detailed and cost-free consultation where we can discuss your situation and how your company can best leverage our combined decades of experience.


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by Matúš Koronthály