Office 365 Tenant to Tenant Migration Exchange Part 4

In the first part of the blog series, we took a look at the topic of planning and selecting the migration scenario and developed a long-term strategy based on the business and technical requirements and defined how the tenant migration should be implemented schematically.

This is a multi part article with the following parts:

• Office 365 Tenant to Tenant Migration Fundamentals Part 1
• Office 365 Tenant to Tenant Migration Identity Planning Part 2

This section is about Exchange / Exchange online or hybrid and the migration and scenarios.

Email services are one of the most important means of communication in any company and are often also involved in business-critical processes. Based on the intensive use and integration of Exchange Online, we take a closer look at the migration requirements in order to prepare for the best possible migration of users/data.

As with identity, the fundamental architecture in Exchange Online is also an important question. That is, what does the current infrastructure look like: Exchange OnPremise, Exchange Hybrid or Exchange Online, and what does the target infrastructure look like?

Overview

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Based on these assumptions and current technical conditions, we can plan a tenant-to-tenant migration.

Let's take a closer look at some scenarios in this blog post.

1. Exchange OnPremises

If we start from a source tenant with a pure on-premises Exchange infrastructure and this will continue to be operated to the same extent in the future, we should have a large task at this point and can concentrate on migrating the other Office 365 services.

The situation is a little different if we want to switch from on-premises Exchange to Office 365 / Exchange Online using tenant-to-tenant migration. In this case, we first need to address some fundamental questions.

Organisational matters and compliance

• Does the target tenant meet the company requirements?
• This could be, for example, retention policies that are permanently defined in the target tenant and applied to all mailboxes. Furthermore, there may also be restrictions in the area of disclaimer and signature integration.
• Operational tasks and assignment?
• With the migration to Exchange Online, some previous tasks such as server , Exchange Database / DAG Management

2. Exchange Hybrid

Within an Exchange Hybrid infrastructure, a tenant-to-tenant migration can become more complex. Since primarily the source and target Exchange environment should be checked.

If, for example, there is also a hybrid infrastructure in the target environment with another Exchange OnPremise infrastructure, then you have to consider a different migration path, since only one hybrid connection is possible.

3. Exchange Online

From the point of view of a tenant migration, Exchange Online is usually the simplest option for implementing this, since all the data is already within the Microsoft cloud and therefore only needs to be migrated to another tenant. Furthermore, integrations are easier to establish in this case as well, since cloud (Exchange Online) services were already connected and these only need to be adapted using different policies and authorisations and routes.