Microsoft’s Outlook email client has been making some macOS users worried this week. When accessing Outlook in Safari, the browser downloads a mysterious “TokenFactoryIframe” file, which some people believed to be malware or something potentially dangerous to their computer. However, this doesn’t seem to be the case.

As reported by Windows Latest, most of the complaints were seen on Reddit. According to multiple users, Safari downloads a file called “TokenFactoryIframe” every time they access Outlook via the web. The file has no extension and cannot be opened by any app.

Although 9to5Mac was unable to reproduce the issue, there are a significant number of users who have been seeing this unknown file on their Macs after accessing Outlook.

I use Outlook on the web when I want to check my work email from home. Beginning today, every time I open Outlook on the web, my browser (Safari, on a MacBook Pro) downloads a blank text document titled “TokenFactoryIframe”. It does this over and over again without prompting me or anything. It does not happen on my work computer (Google Chrome, on a PC).

Luckily for users, the file is completely harmless as it doesn’t have any content. A Microsoft spokesperson confirmed that the company is now aware of a bug affecting Outlook users in which the web browser forcefully attempts to download an internal token. More specifically, the company also confirmed that the bug only affects Safari users.

Microsoft recommends that users access Outlook through another web browser until the bug is fixed. However, a possible workaround is to block all downloads from the Outlook website by going into the Safari settings. Just follow the steps below:

  1. Click on the Safari menu and then click on Preferences.
  2. Go to the Websites tab.
  3. Select the Downloads option in the sidebar.
  4. Look for Outlook and change its permission to Deny.

Have you been affected by this Outlook bug? Let us know in the comments below.

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About the Author

Filipe Espósito

Filipe Espósito is a Brazilian tech Journalist who started covering Apple news on iHelp BR with some exclusive scoops — including the reveal of the new Apple Watch Series 5 models in titanium and ceramic. He joined 9to5Mac to share even more tech news around the world.