Future-proof email communication: migration from Exchange 2016 to Microsoft 365

End of support for Exchange 2016 - jovoco set the course early and successfully migrated to Microsoft 365

Customer

Customer benefits

Technology stack

Microsoft 365
Exchange Server 2016 (on-premises, source system)
Entra ID & Active Directory Synchronization
Hybrid Configuration Wizard (HCW)
PowerShell for batch and migration scripts
Reddoxx e-mail relay

"The migration from Exchange to Microsoft 365 was carried out professionally by jovoco. Despite the complex initial situation, the migration went smoothly, without any interruptions for our teams."

IT management

Challenges of the customer

With the announced end of support for Exchange Server 2016 and 2019 in October 2025, the company was faced with a critical decision: to continue operating local systems with increasing costs and risks – or to switch to a modern cloud platform.

The initial situation was complex: around 100 employees at three locations were using Exchange 2016 on-premises, combined with a local Active Directory. Microsoft Teams was already in use at the same time, which led to duplicate accounts, license overlaps and inconsistent user management.

Particularly challenging: due to the existing Teams licenses, there were already hidden mailboxes in the cloud in the background. This made the migration more difficult, as the existing structures had to be synchronized with the local mailboxes.

The aim was therefore to consolidate the entire mail and user administration on Microsoft 365 – without data loss, without interrupting ongoing operations and with a clear perspective for IT security and compliance.

Our approach

Project planning

The objectives, license requirements and migration strategy were coordinated with the customer. In addition to more than 60 Microsoft 365 standard licenses, additional Teams and Business Premium licenses were added to cover all use cases.

Active Directory Synchronization

The local Active Directory was synchronized with Entra ID. This involved merging existing local user accounts with accounts already created in the cloud. Specifically, passwords and login data were standardized in order to avoid duplicate accounts and ensure a uniform login for all employees. This step was sensitive, as incorrect settings can lead to temporary login problems, but was successfully implemented through targeted testing and clear communication.

Hybrid configuration & migration paths

The Hybrid Configuration Wizard (HCW) was used to establish the connection between Exchange 2016 and Microsoft 365. Special cases such as shared mailboxes and meeting rooms were also taken into account.

Test migration & workarounds

Individual mailboxes were migrated on a test basis to validate processes. A key challenge was that MS Teams had already created invisible Exchange mailboxes in the cloud. To resolve these conflicts, we temporarily assigned a Business Standard license to the affected users and then removed it again. This increased the automatically created mailboxes to 50 GB so that they could be used as a target for the migration. This pragmatic approach ensured that all mailboxes could be transferred successfully and without data loss.

Go-live & aftercare

The final migration was carried out in stages, accompanied by communication and support for end users. After project completion, tenant hardening measures were planned to increase the Microsoft Secure Score and establish security guidelines.

Results for the customer

Productive downtime during the changeover

0 Hours

of mailboxes successfully migrated

0 %

Further results:

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