Fourth experienced a major incident on September 4, 2026 affecting Analytics and Applicant Tracking System (ATS) and 1 more component, lasting 3h 47m. The incident has been resolved; the full update timeline is below.
Affected components
Update timeline
- investigating Sep 04, 2026, 12:37 PM UTC
We are aware of an issue that is impacting our ability to send emails. Starting around 08:00 UTC, Microsoft began experiencing an incident causing an increased volume of deferred emails across all M365 regions. The affected responses are returning "451 4.7.500 Server busy". Our teams are actively monitoring the situation. No other email providers are currently affected. Please also see https://downdetector.co.uk/status/outlook/ PLEASE NOTE: This could impact and is not limited to Orders Reports Employee updates Password resets. We strongly suggest that customers consider invoking their DISASTER RECOVERY PROCEDURES for their most important functions and if you need to ensure orders are received, telephone contact is recommended. More information will be provided as it becomes available.
- identified Sep 04, 2026, 12:38 PM UTC
We are aware of an issue that is impacting our ability to send emails. Starting around 08:00 UTC, Microsoft began experiencing an incident causing an increased volume of deferred emails across all M365 regions. The affected responses are returning "451 4.7.500 Server busy". Our teams are actively monitoring the situation. No other email providers are currently affected. Please also see https://downdetector.co.uk/status/outlook/ PLEASE NOTE: This could impact and is not limited to Orders Reports Employee updates Password resets. We strongly suggest that customers consider invoking their DISASTER RECOVERY PROCEDURES for their most important functions and if you need to ensure orders are received, telephone contact is recommended. More information will be provided as it becomes available.
- identified Sep 04, 2026, 01:01 PM UTC
We are aware of an issue that is impacting our ability to deliver emails to customers that use outlook.com / outlook365.com as their mail provider. Starting around 08:00 UTC, Microsoft began experiencing an incident causing an increased volume of deferred emails across all M365 regions. The affected responses are returning "451 4.7.500 Server busy". Our teams are actively monitoring the situation. No other email providers are currently affected. Please also see https://downdetector.co.uk/status/outlook/ PLEASE NOTE: This could impact and is not limited to Orders Reports Employee updates Password resets. We strongly suggest that customers consider invoking their DISASTER RECOVERY PROCEDURES for their most important functions and if you need to ensure orders are received, telephone contact is recommended. More information will be provided as it becomes available.
- identified Sep 04, 2026, 01:58 PM UTC
We are starting to see a gradual improvement in the situation and emails are starting to appear. Please note, it will take some time for the backlog of messages to process and we have received no formal notification of resolution at this stage. Further updates will be provided as they become available.
- resolved Sep 04, 2026, 04:25 PM UTC
Microsoft, via X, stated 12 minutes ago, "We've applied the mitigations and confirmed the issue resolved after an extended period of monitoring. Further information is provided under EX1467029 in the admin center" No further updates will be provided.