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Migration and Modernization

Exchange On-Premises to Exchange Online Migration

Exchange 2016 and 2019 reached end of support in October 2025. Each month they stay on-premises adds security risk and server cost. RHC moves your mailboxes to Exchange Online with a hybrid setup, so users keep working and mail keeps flowing during the whole migration.

The challenges

  • Exchange 2016 and 2019 no longer get security updates, which leaves the servers exposed to known attacks.
  • Applications, scanners and devices that send email through Exchange over SMTP relay have to keep working.
  • Users on-premises and in the cloud need shared calendars, free/busy and one global address list.
  • Public folders and shared mailboxes need their own migration paths and a permission review.
  • Many companies don't know whether they can remove the last on-premises Exchange server.

How we do it

  1. 1Assessment: Exchange version, mailbox sizes, public folders, connectors, SMTP relays and certificates.
  2. 2Identity: Entra Connect setup or review, so users have a single identity in both environments.
  3. 3Hybrid configuration: hybrid setup for free/busy, secure mail flow and remote mailbox moves.
  4. 4Pilot: IT and key users move first to validate Outlook, mobile and mail flow.
  5. 5Mailbox migration in batches: moves run in the background and complete in planned windows.
  6. 6Mail flow and MX cutover: MX points to Exchange Online Protection, relays move to the cloud.
  7. 7Decommissioning: we retire the servers or keep the minimum management footprint, as supported by Microsoft.

What’s included

Hybrid Exchange configuration and Entra Connect review
Mailbox, archive and shared mailbox migration
Public folder migration to Exchange Online or Microsoft 365 Groups
SMTP relay redesign for applications, printers and scanners
Email security: Defender for Office 365, SPF, DKIM and DMARC
Server decommissioning plan

Why RHC

Long track record with Exchange, from on-premises versions to Exchange Online
Deep experience with hybrid mail flow and SMTP relay alternatives
Email security configured as part of the project
Fixed-scope proposals with a clear migration calendar

Frequently asked questions

No. Both reached end of support on October 14, 2025, and no longer receive security updates.

Coming from IMAP instead of Exchange

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