Exchange Server 2016/2019 End of Life: Key Impacts and Migration Options

Posted by Team Transvault on Oct 24, 2025 Last updated Oct 24, 2025

Microsoft Exchange Server 2016 and 2019 reach end of extended support yesterday, 14 October 2025. There’ll be no more security updates, bug fixes, or technical support. That might sound like just another IT milestone, but for the thousands of companies still using these versions, it’s far more than that. The servers will still run and email will still flow, but without updates, they’ll become a security and compliance risk. Think of it like driving a car that’s no longer being serviced, it may keep going, but every mile increases your exposure to danger.

If your organisation is still on Exchange 2016 or 2019, this is your moment to plan.

What Happens Now?

Once support ends, Exchange 2016 and 2019 will no longer receive updates or patches. The impact is straightforward:

  • Security vulnerabilities go unpatched – making attacks more likely.
  • Compliance gaps widen – especially for organisations under GDPR or HIPAA.
  • Reliability declines – as there’s no vendor safety net for issues.
  • Post-exploit actions – Attackers establish persistence, move laterally, steal credentials, deploy ransomware or exfiltrate data.
  • Mass scanning & initial compromise – Automated tools start compromising exposed hosts at scale.

Many organisations have already migrated. But for those who haven’t, using an unsupported mail system leaves your companies mailboxes open to significant risk.  It only takes one malicious email to get through and the data is compromised.

Your Options Going Forward

Microsoft offers two main routes:

  1. Exchange Online (Microsoft 365): Always up-to-date, secure, and managed in the cloud.
  2. Exchange Server Subscription Edition (SE): A new on-premises option due later in 2025, with a subscription model and ongoing updates.

Both provide a chance to modernise your email environment while improving resilience and reducing future risk.  Alternatively you consider a migration to a different vendor altogether, such as Google (But this will require further planning).

Five Smart Steps for a Smooth Migration

Migrating isn’t just an IT task, it’s a change programme. Here’s a simple, proven approach:

  1. Update your security policies – Review password rules, enforce multi-factor authentication, and clean up old permissions.
  2. Communicate early – Let teams know what’s happening and why. Transparency helps build confidence.
  3. Support mobile users – Reconfigure devices and create clear guides to help everyone reconnect post migration.
  4. Assess your options – Microsoft 365 or Google Workspace – choose what truly fits your organisation’s future.
  5. Budget wisely – Factor in migration, licensing, and support so you’re ready for the change.

A Chance to Rethink, Not Just Replace

For some, moving to Exchange SE will feel like the right balance. For others, a fully cloud-native setup offers simplicity, flexibility, and lower overheads. Whatever the choice, preparation is key:

  • Back up Exchange and Active Directory.
  • Plan for potential downtime.
  • Optimise your infrastructure footprint to manage cost.
  • Test rollback procedures before go-live.

Risk & Cost Trade Offs

  • Do nothing – high probability of compromise, potential for severe data loss and major costs later.
  • Short-term mitigations only – reduces risk temporarily but still vulnerable.
  • Immediate migration/upgrade – highest upfront cost but lowest long-term risk and total cost of ownership.

Start Preparing Now

Start now by:

  • Auditing your existing email setup.
  • Identifying legacy or hybrid dependencies.
  • Documenting your plan and timeline.
  • Getting expert help.

The Bottom Line

Exchange 2016 and 2019 have served businesses well, but their time is up. This isn’t about rushing change; it’s about planning smartly. Move as soon as possible, migrate securely, and future-proof your communication.

At Transvault, we’ve spent years helping organisations migrate with confidence. Whether you’re heading to Exchange Online or another modern platform, we’ll help you make the move securely and seamlessly – without disruption. Want a hand? Get in touch with our experts to get started today – Speak To An Expert