If your business still runs its own Exchange mail server, you have a decision to make before the end of October 2026. Microsoft stopped supporting Exchange 2016 and Exchange 2019 last year. The paid cover that replaced it is about to run out.
Exchange Server end of life happened on 14 October 2025. Since then the only way to get security fixes has been to buy Extended Security Updates, and the last of those stop at the end of October 2026. Microsoft has confirmed nothing follows. From November you have two supported choices: move mail to Microsoft 365, or upgrade to Exchange Server SE.
Microsoft’s own advice is blunt. In the notice announcing the final round of paid updates, the Exchange team said they would rather not sell it to anyone, and asked customers to migrate instead.
When Did Exchange Server Support End?
Exchange Server end of life came on 14 October 2025. It covered both Exchange Server 2016 and Exchange Server 2019, and Microsoft’s lifecycle pages list the same date for each. From that day there were no more security updates, no bug fixes and no technical support.
What happens when Exchange Server support ends is easy to miss, because nothing breaks. Mail keeps flowing. If you are still hosting your own mailboxes, you are not getting ready for a deadline. You missed one almost a year ago, and a paid add-on has covered you since.
Why Does This Matter Now?
Because that paid cover ends with October 2026 and nothing replaces it. Until now, a business that missed the 2025 date could buy Extended Security Updates and keep getting critical fixes. From November that option is gone, at any price, for good.
An Exchange server is not like an old file server sitting quietly inside your network. It publishes services to the internet so that phones and Outlook can reach it. A flaw found after October can be reached from anywhere, by anyone looking, and Exchange has a long record of flaws being attacked within days of becoming public. Transputec sees the same pattern across the managed IT estates it looks after: the mail server is the last thing to be modernised and the first thing to be probed.
Still Running Your Own Exchange Server?
Transputec moves mailboxes around the business, not the other way round. For Incisive Media it moved 130 user mailboxes and 100 shared mailboxes in a single weekend, after a week of preparation. Talk to our team about the work behind moving off Exchange Server.
Get a Strategic ConsultationWhat Are Your Options for Exchange Server End of Life?
Two options leave you supported, and two do not. You can move mail to Microsoft 365, or stay on your own hardware and upgrade to Exchange Server SE. Buying the last paid updates only helps until October. Doing nothing leaves an unpatched server facing the internet.
| Option | What it means | Supported after October 2026 |
|---|---|---|
| Microsoft 365 (Exchange Online) | Microsoft hosts your mailboxes. No mail server to patch. Paid per user, per month. | Yes |
| Exchange Server SE | Mail stays on your hardware. The current version, bought through volume licensing. | Yes |
| The last paid updates | Critical fixes only, if Microsoft releases any. Enterprise Agreement customers only. | No, it ends with October 2026 |
| Do nothing | A working mail server with no security fixes behind it. | No |
One point the table hides. Exchange Server SE is not a new product you have to learn. It is the same Exchange, continued under a subscription licence, which is why moving to it from Exchange 2019 is so straightforward.
Should We Move From Exchange Server to Microsoft 365?
For most businesses, yes. Keeping your own mail server only makes sense if you have a specific reason: a rule about where data must sit, an application that needs a local Exchange, or a site where the internet connection makes cloud mail a daily argument.
If none of those apply, running your own mail is a cost you are choosing. You pay for the hardware, the Windows Server licences, the certificates, the patching and the late-night calls when a database goes offline. Microsoft 365 turns that into a per user, per month line, and removes the internet-facing server that made Exchange Server end of life such an urgent problem.
Hybrid setups deserve a word, because many businesses already have one. Hybrid is a way to move, not a place to stay. It lets you shift mailboxes gradually and then switch the old servers off. Leave one running and you still own an Exchange server that needs patching.
How Do You Upgrade to Exchange Server SE?
It depends on which version you run today, and the difference is large. Microsoft’s upgrade guidance gives two routes. If you are on Exchange 2019 the upgrade is simple. If you are on Exchange 2016 it is a rebuild, and that needs planning.
- Exchange 2019: upgrade in place. If your server is on Cumulative Update 14 or 15, Exchange Server SE installs straight over the top, much like applying a normal update. Microsoft calls this low risk. It is the reason to get your 2019 servers current now.
- Exchange 2016: build new, then move. You add new servers alongside the old ones, move every mailbox across, then remove the originals. You need this route as well if you are changing hardware or moving to a newer version of Windows Server.
Two rules catch people out. Exchange Server SE will not install alongside Exchange 2013, and from its second update it refuses to sit alongside any version that is out of support. Keeping an old server around to satisfy one application will eventually block your own upgrades. Microsoft’s Exchange Server Deployment Assistant builds a checklist for your exact starting point, which is worth running before you book the work. For most estates the Exchange Server end of life decision is that simple: upgrade in place, or rebuild alongside.
What Do the Last Paid Updates Actually Cover?
Less than most people assume. Microsoft ran one round of Extended Security Updates from October 2025 to April 2026, then announced a second running from May 2026 to the end of October 2026. The notice says plainly that there will be no further extensions.
The conditions matter as much as the dates. The second round is a separate contract, so businesses already signed up for the first had to buy again. It is only for customers on a Microsoft Enterprise Agreement. It only covers Exchange 2016 on Cumulative Update 23, and Exchange 2019 on Cumulative Update 14 or 15. And it only delivers fixes Microsoft rates as critical or important.
One line is worth reading twice. Microsoft is not promising to release any updates at all during this period. You are buying the right to receive fixes that may never come, for a few weeks. As a bridge while a migration is already booked, that is sensible. As a plan, it is not. Paid updates are the most expensive way to put off Exchange Server end of life, and they stop with October 2026.
What Does an Exchange Migration Involve?
Less drama than most teams expect, as long as the groundwork is honest. What derails these projects is rarely the mailboxes. It is the things quietly tied to the mail server: the scan-to-email on the copier, alerts from a business application, shared mailboxes nobody owns, old public folders.
An Exchange Server migration follows a simple order, and the first two steps take most of the time.
- List everything that uses Exchange. Mailboxes, shared mailboxes, distribution groups, public folders, and every device or script that sends mail through the server.
- Decide by mailbox type, not by person. Shared and meeting-room mailboxes often move differently from staff mailboxes, and public folders need their own decision.
- Sort out the printers and scanners early. Anything that sends mail through Exchange needs a new route before the server goes. This is the most common cause of a bad cutover.
- Move in batches, then switch off. Start with a pilot group, check mail and phones still work, then move everyone else in waves and set a date to retire the old servers.
Size is rarely the problem. Transputec’s Microsoft 365 migration for Incisive Media moved 130 user mailboxes and 100 shared mailboxes across one weekend, after a week of preparation and a written plan. That preparation is what made the weekend quiet, and it is the same preparation Exchange Server end of life now asks of everyone still hosting their own mail.
Your Exchange Server End of Life Checklist
Work through these in order.
- Check your version and update level. Exchange 2019 on Cumulative Update 14 or 15 can upgrade in place to Exchange Server SE. Anything else cannot.
- Find out whether you hold the second round of paid updates, and put the end of October 2026 in the diary as a hard stop.
- List everything that sends or receives mail through the server, including printers, scanners and monitoring tools.
- Choose the destination for each workload, and write down the reason for anything staying on your own hardware.
- Plan how the old servers get switched off, not simply how the mailboxes move. A hybrid server left running is still yours to patch.
- Book the work early. A lot of businesses are doing this in the same few months.
If the answer is that mail should move to Microsoft 365, the cloud migration work is well understood and is usually measured in weeks.
Conclusion
Exchange Server end of life is not something to plan for. It happened on 14 October 2025, and the paid cover that followed ends with October 2026. After that there is no way to get a security fix for Exchange 2016 or 2019 at any price.
The choice left is simple. Either mail moves to Microsoft 365, or it stays on your hardware and you upgrade to Exchange Server SE for a reason you could explain to an auditor. The businesses that handle this calmly are the ones that made the list first, decided by mailbox type, and treated the printers and applications as the real work. Transputec does this with clients as part of modern workplace projects, and the mailbox move is usually the least surprising part.
FAQs
When Did Exchange Server 2016 and 2019 Support End?
14 October 2025, for both. Exchange 2016 end of support and the 2019 date fell on the same day, and Microsoft’s lifecycle pages list it for each. From that point there were no security updates, no bug fixes and no technical support outside the paid updates you could buy.
Can I Still Buy Security Updates for Exchange?
Only the second round, and only until the end of October 2026. It is a separate purchase rather than a renewal of the first. It is for customers on a Microsoft Enterprise Agreement, and it covers Exchange 2016 on CU23 and Exchange 2019 on CU14 or CU15. Nothing follows it.
Can I Upgrade Exchange 2016 Straight to Exchange Server SE?
Not in place. The in-place upgrade only works from Exchange Server 2019 on Cumulative Update 14 or 15. From Exchange 2016 you build the new servers alongside the old ones, move every mailbox across, then remove the originals.
Is Exchange Server SE a Different Product?
Not really. Exchange Server SE is the same Exchange, continued under a subscription licence rather than a one-off purchase. That is why upgrading from Exchange 2019 feels like applying an update. The real differences are in how it is licensed and which old versions it will sit alongside.
What Happens If We Do Nothing Before November 2026?
Mail keeps working. Your security cover does not. From November 2026 there is no way to get an update for Exchange 2016 or 2019 at any price. Transputec treats that as the real deadline for Exchange Server end of life, because the server faces the internet and every new flaw stays open.
This article was drafted with AI assistance and reviewed by the Transputec team. Featured image: AI-generated.
