When I try to open an attachment that is an excel, in Excel 2019, from Outlook, I get the message that it cannot open the file because it is corrupt. If I save the file to my computer I get the same thing. If I go into File/Options/Trust Center/ Trust Center Settings/Protected View and uncheck the 3 boxes then it will open the file on my computer. My other computer has these boxes checked and it has no problem opening these files. Note: the other computer has Office 2019 also.