Outlook may open a pop-up window for certain e-mails and ask if you are sure you want to open this type of attachment and trust the source. The message can be deactivated by checking the box "Always confirm before opening this file type".
But what if this checkbox cannot be selected? What if the field is grayed out?
With the following workaround you can disable this message for the future. This is how it works:
Disable Always confirm before opening this file type
You must run Outlook.exe as administrator. Navigate as follows to one of the following two subdirectories (depending on the installation location)
- C:\Programs\Microsoft Office\[VERSION]
Here you can find the Outlook.exe. Now you have to click on it with the right mouse button and then select "Run as administrator".
Open the e-mail with the attachment. The message is displayed.
Now the check mark at "Always confirm before opening this file type" can be deactivated.
The message is no longer displayed when opening attachments.