Sending, receiving, and organizing email in Outlook.com
Hi,
Thanks for reaching out. There’s a known issue with Outlook Online in Firefox that started around noon EST on November 5, 2025. When visiting outlook.office.com/mail, the page shows raw HTML instead of the normal interface, though it works fine in Chrome.
Microsoft hasn’t confirmed the cause yet, but it’s likely a browser rendering bug or a server-side configuration issue.
In the meantime, try clearing Firefox’s cache and cookies, disabling extensions, or using Private Mode. You can also switch to Chrome or Edge temporarily and make sure Firefox is up to date. If the problem persists, report it to Microsoft through their support channels.
Please visit this article for more information- https://support.microsoft.com/en-us/office/fixes-or-workarounds-for-recent-issues-in-classic-outlook-for-windows-ecf61305-f84f-4e13-bb73-95a214ac1230
Hope this helps,
Regards,
Edward