Microsoft to Block Dangerous Embedded OneNote Files on Windows

To improve security against high-risk phishing file types, Microsoft will be blocking embedded OneNote files with potentially dangerous extensions. Please note this change will only affect the OneNote app on Windows – this change will not affect OneNote on Mac, OneNote on Android or iOS devices, OneNote on the web, or OneNote for Windows 10*. 

This change will start rolling out late April 2023 and is expected to be complete by May 2023. The list of blocked file types for OneNote will be consistent with the file types currently blocked in Outlook, Word, Excel, and PowerPoint.

WHAT WILL CHANGE

Currently when you try to open a harmful attachment in OneNote, you'll receive a pop-up that warns you that the attachment you're trying to open may be harmful, but you are able to open the attachment by clicking 'OK'.

After this change is rolled out, you'll receive a pop-up that says "Your administrator has blocked your ability to open this file type in OneNote" when you try to open a harmful attachment, and you will not be able to open the attachment in OneNote.

If you trust the sender of the file and want to proceed with opening the potentially harmful attachment, you will need to save and open the file on your computer.

RESOURCES

*Not sure which version of OneNote you're using on Windows? Read about the differences between OneNote and OneNote for Windows 10.