Do emails sent during Microsoft's global outage get delivered or are they lost forever? Here's what happens

Microsoft Outlook users around the world were disrupted recently as a widespread outage affected access to email accounts, with many unable to send or receive messages or load their inboxes. The outage also impacted wider Microsoft 365 services, raising questions around what happens to emails sent while the platform is suffering such technical issues.

However, an outage does not mean that emails are permanently lost. Whether or not a message reaches its intended recipient depends on where in the delivery process the disruption occurred.

What happened during Microsoft's Outlook outage?

The outage began around 1pm ET on Thursday, with Downdetector getting more than 100,000 reports of problems getting into Outlook. That number later fluctuated, with the Associated Press reporting nearly 130,000 complaints shortly after the outage began.


Users stated that they were struggling to open their inboxes, send emails and receive incoming messages. Microsoft Teams, SharePoint Online, Microsoft 365 and Copilot also experienced problems, though the issues were different in severity and location across the services.

The disruption also caused ripple effects beyond Microsoft’s own apps: third-party AI platforms, including OpenAI and Anthropic, reported broken mail, calendar and search connectors tied to Microsoft 365 during the incident.

Microsoft confirmed that users in the Americas are experiencing issues with accessing Exchange Online mailboxes via multiple connection methods. The company later determined that connectivity problems were likely caused by an overburdened section of its infrastructure. As per CNA, to fix the problem, Microsoft stopped all deployments and configuration changes, re-routed traffic from affected infrastructure and rebooted servers to restore services.

Earlier, Microsoft said that it was reviewing an unexpected increase in a specific type of service traffic but later shared an update on X stating, "We determined the elevated load isn't driven by an increase in traffic, but by a number of servers being unexpectedly unavailable; straining the remaining infrastructure."

What happens to emails sent during the outage ? Are they lost forever ?

If Outlook is down, that doesn't mean that the messages sent while it was down are lost forever. Instead, what happens to your email most probably falls into one of three scenarios depending on where it was when the servers stalled:

If you find the email in your Outbox: The message never got out of your device. In this case, once the connection is restored users can try synchronising Outlook or manually send the message again. Automatic resending is not always guaranteed.

If you sent an email just as servers stalled: If a message has reached Exchange Online but faces a temporary delivery failure, Microsoft's mail system may retry sending it rather than immediately rejecting it. As per Microsoft support, error code 4.4.7 covers temporary failures which will be retried for up to 24 hours before a bounce-back non-delivery report (NDR) is generated. This 24-hour period applies to this particular type of temporary delivery failure, not necessarily every email affected by the outage.

If someone outside (like a Gmail user) emailed you while Outlook was down: The sender's email provider stores it in its own retry queue and usually attempts delivery for some time and then drops it into your inbox once Microsoft's servers respond again. However, retry periods vary between providers, and delivery is not guaranteed.

Basically, emails don’t just disappear without a trace; they either get delayed in a retry queue or get returned with a failure notification if delivery ultimately fails.

How to check if your email has been delivered

When access is restored, normal users should begin by opening Outlook on the web and checking both Sent Items and Outbox folders. Looking at the web version ensures that you see the actual status of the server and not old local cache information from a desktop or mobile app. Any messages that are still in the Outbox will have to be sent again manually.

For organizations that require more confirmation, Microsoft provides a tool called Message Trace through the Exchange admin center. Authorised administrators can use this tool to investigate what happened to a particular email.

According to Microsoft, newly sent messages typically take five to 10 minutes to appear in message trace data, where admins can see if a message was delivered, failed, or is pending. Message trace data is retained for 90 days, and you can search any messages sent during that time.