The latest version of Microsoft Exchange is still 2019, with supporting Cumulative Updates (CUs) released quarterly by Microsoft.
To move to Office 365 there are two typical approaches:
1. Cutover Migration
For this approach the user identities would typically be migrated to M365 Azure AD, and all mail data manually copied to Exchange Online – from the local client, or using the AZCOPY PST migration tool.
Once the hybrid migration completes and mailboxes are in Exchange Online, the next problem is the M365 environment itself. ShareGate gives IT admins visibility into what landed: permissions inheritance across SharePoint and Teams, externally shared content, ungoverned sites, and whether the environment meets the bar for Microsoft 365 Copilot. None of that is covered by the Hybrid Connectivity Wizard.
Exchange 2019 environments tend to be tightly managed on-prem. M365 is open by default. ShareGate bridges that gap — surfacing what’s exposed, flagging broken permissions, and giving admins a clean baseline without requiring manual site-by-site investigation or custom PowerShell.
2. Hybrid Migration (Recommended)
This is the most common approach and allows for Exchange 2019 to coexist with Office 365 for address book, mail flow, and identity. The on-premise AD user remains the master identity, and the Microsoft Hybrid Connectivity Wizard (HCW) is used to connect Exchange 2019 to Exchange Online. Care is needed over an appropriate SSL certificate, and DNS changes. However, once achieved, the mailbox moves can be done in a phased manner, and mailboxes moved back easily also.
There are other considerations around SMTP relay requirements, and DKIM/DMARC also.
Exchange On-Premise Management
An on-premise Exchange 2019 server is required on-premise to support user management of email attributes however, with Microsoft only supporting this being removed if you want to use powershell instead.
Use our expert Office 365 migration services to transition off Exchange to Microsoft 365.