With the Microsoft 365 outage affecting Exchange Online and other services over the past day, I thought this would be a good time to discuss something that seems increasingly unpopular in IT: running your own Exchange servers.
I'm an IT Director for a manufacturing company with multiple facilities, and we've continued operating Exchange on-premises rather than moving our email infrastructure to Microsoft 365.
And days like yesterday remind me why.
While organizations relying on Exchange Online were dealing with mailbox connectivity problems and service interruptions, our Exchange environment remained operational. Our employees could continue using Outlook, accessing their mailboxes, and communicating internally without depending on Microsoft's cloud infrastructure being available.
Obviously, we can't control whether external organizations can send or receive their email, but at least our own mail system wasn't part of the outage.
There are still some significant advantages to running Exchange on-premises:
Control over our infrastructure
We control our servers, maintenance schedules, updates, backups, and recovery procedures. We aren't dependent on Microsoft resolving a cloud infrastructure problem before our users can access their mailboxes. Our email environment operates independently of Exchange Online. A Microsoft 365 outage doesn't automatically mean our employees lose access to email. This doesn't eliminate every possible dependency, but it does remove a major one.
We have a solid backup schema and maintain our own disaster recovery procedures. We control our backup retention, recovery testing, and restoration priorities. If something goes wrong, we can investigate and initiate recovery ourselves rather than waiting for a cloud provider to restore service. We determine when to perform maintenance, deploy updates, and make infrastructure changes. We can coordinate those activities around manufacturing operations rather than having changes introduced into our email platform outside our control. Our mailboxes and Exchange databases reside within infrastructure we manage. We maintain direct control over how that data is stored, protected, backed up, and recovered.
We already maintain servers, virtualization infrastructure, security tools, and backup systems for other business-critical applications. Exchange fits into that existing environment. We're not building an entirely separate infrastructure just to host email. Now, I'm not pretending on-premises Exchange is perfect.
There are real disadvantages. Patching, vulnerability management, certificate management, availability, disaster recovery, and security are entirely our responsibility. Exchange has also been a frequent target for attackers, and running an outdated or poorly maintained Exchange environment is a significant liability. With Exchange 2016 and 2019 out of support, organizations staying on-premises also need to account for Exchange Server Subscription Edition and its licensing and maintenance requirements. For smaller organizations without dedicated IT resources, Exchange Online probably makes considerably more sense.
But I think we've reached a point where cloud-first has become cloud-by-default, and those aren't necessarily the same thing.
Cloud hosting can reduce operational responsibilities, but it also transfers certain aspects of control to another organization. When that organization has a major outage, there may be very little you can do besides monitor the incident and communicate with your users. I don't believe on-premises infrastructure is automatically better than cloud infrastructure. I believe the right decision depends on the organization, its technical capabilities, its business requirements, and its risk tolerance.
For us, a capable internal IT department and established infrastructure make maintaining our own Exchange environment a reasonable decision. And watching the Microsoft 365 issues unfold has certainly reinforced the value of that independence.
I'm curious how many other organizations are still running Exchange on-premises in 2026. Are you staying on-premises intentionally, running a hybrid environment, or planning to migrate everything to Exchange Online? For those who have migrated, has the reduction in administrative overhead been worth giving up direct control over your email infrastructure?