When you download files from the Internet, Windows 11 shows you a security warning every time you try to open it by default. Some file types are blocked from opening.
The Attachment Manager is included in Windows to help protect your PC from unsafe attachments that you might receive with an e-mail message and from unsafe files that you might save from the Internet. If the Attachment Manager identifies an attachment that might be unsafe, the Attachment Manager prevents (blocks) you from opening the file, or it warns you before you open the file.
It uses the IAttachmentExecute application programming interface (API) to find the file type, to find the file association. When one of these applications saves a downloaded file on a disk formatted with NTFS, then it updates the metadata for the file with the zone it was downloaded from. The metadata is saved as an Alternate Data Stream (ADS). If you wish to unblock a downloaded file, you can do so by right-clicking it, selecting Properties and clicking on Unblock.
The Attachment Manager classifies files that you receive or that you download based on the file type and the file name extension. Attachment Manager classifies files types as high risk, medium risk, and low risk.
This tutorial will show you different ways on how to unblock files downloaded from the Internet depending on how they were blocked in Windows 11.