Microsoft 365 went down. Could your email keep running?

When Microsoft 365 goes down, there’s not much an IT team can do to bring Microsoft 365 back up.

But that doesn’t mean the only option is to wait.

The November 2026 Microsoft 365 outage was another reminder of just how much business now runs through a handful of cloud platforms. The disruption affected Outlook, with issues reported across Teams, SharePoint, Copilot, and Defender. According to Mimecast, Outlook and Teams were disrupted for more than 10 hours.

When a service like email becomes unavailable, the impact can spread quickly. Internal conversations stop. Customer emails go unanswered. Sales reps lose a primary way to communicate. Support teams suddenly have fewer ways to reach the people who need them.

For many businesses, that scenario became very real this week.

And while Microsoft worked to fix the problem, IT teams were left answering a much more immediate question:

How do we keep working?

For email, there’s an answer. But it requires planning for an outage before one happens.

The cloud didn't eliminate downtime

Microsoft 365 has removed a huge amount of infrastructure burden from IT teams. Organizations don't have to maintain their own Exchange servers or build the same level of redundancy they once did.

That's a good thing.

But there's an easy assumption hiding inside that convenience: Microsoft handles availability, so Microsoft handles continuity.

Those aren't quite the same thing.

When Microsoft experiences a service interruption, customers largely have to wait for Microsoft to restore it. You can't reboot Microsoft's servers or fail Exchange Online over to a secondary data center yourself.

What you can control is what happens to your business in the meantime.

That's where email continuity comes in.

Your Microsoft 365 email doesn't have to be all or nothing

Think about the normal path an email takes.

A customer sends a message. It passes through your email environment and eventually lands in an employee's Microsoft 365 mailbox. The employee replies, and Exchange Online helps move that message back out.

If Exchange Online becomes unavailable and there's no alternate path, email can effectively hit a wall.

Mimecast Email Continuity is designed to give organizations another route.

During an outage, administrators can trigger a continuity event that switches email clients to send and receive messages through the Mimecast platform. Users retain access to email and calendar information, and when the primary email system returns, Mimecast automatically reconnects and synchronizes messages sent and received during the disruption.

That means the outage and your organization's response to it can happen at the same time. Microsoft can be working to restore Exchange Online while your employees keep communicating.

That's an important distinction because this isn't really a backup story.

Backup asks: "Can we get our data back?"

Continuity asks: "Can we keep doing business?"

During an active outage, the second question becomes pretty important.

The catch: You have to prepare before things go down

This isn't something IT should be figuring out halfway through an outage.

Mimecast's continuity solution requires the right email architecture and configuration to be in place ahead of time. When an outage happens, an administrator initiates the switchover to Mimecast so email can continue flowing while the primary system is unavailable.[

That makes an outage like this a worthwhile reason to take a closer look at the current environment.

Not six months from now during a business continuity review. Now, while the question is easy to answer:

If Microsoft 365 email stopped working today, what would we actually do?

That's where IT teams should start digging:

• Who knows how to activate continuity?
• Has anyone tested it recently?
• Can employees continue working from the tools they're familiar with?
• Do email protections remain in place?
• What happens to messages sent while Exchange Online is unavailable?
• When Microsoft 365 comes back, does everything synchronize automatically or does IT inherit a cleanup project?

That last question matters. Mimecast says its Mailbox Continuity service automatically synchronizes email once the primary service is restored, helping reduce the operational burden of returning to normal.

If answering the rest of those questions requires digging through documentation or figuring out who owns what, that's useful information in itself.

An outage can create a security problem too

There's another side to downtime that's easy to overlook.

People don't like sitting around waiting for technology to come back.

If employees can't communicate through normal business channels, they'll look for another way. Personal email, consumer messaging apps and other workarounds can suddenly look pretty tempting.

Now an availability problem has the potential to create a security problem too.

Mimecast makes a similar point in its guidance on Microsoft 365 outages: downtime can affect productivity and disrupt IT teams while increasing corporate security risk as users search for alternate ways to send time-sensitive information.

That's why continuity shouldn't simply mean giving employees some way to send a message. The goal is to keep business communication moving without creating a second problem in the process.

Once Microsoft 365 recovers, email handled through Mimecast Email Continuity can synchronize back to the primary environment.

Ideally, the disruption stays exactly that: a disruption. It doesn't turn into a collection of workarounds and an operational mess on top of it.

Email continuity doesn't make Microsoft 365 outage-proof

It's important to be clear about what this solution does and doesn't do.

Mimecast Email Continuity isn't going to keep every Microsoft 365 service running during a Microsoft outage.

If Teams is unavailable, email continuity doesn't bring Teams back. If SharePoint goes down, it doesn't suddenly make SharePoint accessible.

What it can do is remove email from the list of things your business has to lose at the same time.

And that leads to a bigger question IT leaders should be asking about their cloud strategy.

We spend a lot of time planning for failures inside the infrastructure we control. Servers fail. Storage fails. Networks fail. Data centers can go offline. Those scenarios have long been part of disaster recovery planning.

But more and more business-critical technology now runs on infrastructure someone else controls.

So modern resilience planning has to account for a different kind of failure:

What happens when the technology is healthy on our side, but a cloud service we depend on isn't available?

That conversation shouldn't stop with email.

Map the SaaS applications that would seriously affect operations if they disappeared for several hours. Look at where a redundant path exists and where it doesn't. Understand what the provider's SLA covers, but more importantly, understand what your team will actually do while waiting for service to return.

Sometimes, the answer may simply be to wait.

For business-critical communication, it doesn't have to be.

Before the next outage, ask one question

You don't need to redesign your entire business continuity strategy every time a cloud provider has an incident.

But you should learn something from it.

So start simple: If Exchange Online went down again tomorrow, could your business keep emailing?

If the answer is yes, make sure the process is tested and the people responsible for it know exactly what to do.

If the answer is "I think so," "probably" or "we'd have to check," now is a very good time to check.

And if the answer is no, that's a resilience gap you can actually do something about.

RapidScale can help organizations evaluate their Microsoft 365 email architecture, understand where outages could interrupt communication, and determine whether Mimecast Email Continuity makes sense for their environment.

Because you can't control when Microsoft 365 has an outage.

You can control whether your email has to go down with it.

Send a message to RapidScale now to talk about building email continuity into your Microsoft 365 strategy.