Microsoft recently confirmed a technical error in its Outlook spam filtering rules that caused the system to reject legitimate emails. The issue affected users of Outlook.com, Hotmail.com, Live.com, and MSN.com domains, with reports of delivery failures surfacing around early November.
The root cause was identified as a faulty update to the company's spam filtering criteria. Despite senders having valid SPF, DKIM, and DMARC authentication records, the system incorrectly flagged and blocked their messages. Microsoft has since rolled back the update to restore normal service.
According to the company, email traffic returned to normal operations by 12:02 PM Central European Time on November 9. Microsoft stated that no changes to personal account settings or sender authentication protocols are required, as the fault originated entirely within their own infrastructure.
The company clarified that emails rejected during the incident cannot be recovered. Because the messages were blocked before reaching the server, they were not stored in any inbox or spam folder. Microsoft advises users to contact senders to request that important missing correspondence be resent.
