@duffers5 Is there a "View in SharePoint" option available? (wording might be different, but something that means that). If there is, get one of the ones who can't use it to try that and see if they can open the file there. If they can't its a permissions issue for your IT people.
So it appears #Outlook is on it's last legs. I've used the web version for a long time, and #OneOutlook seems to come from that source rather than just being another version of the desktop client. It's the right move, but some will find it hard, I suspect.
https://t.co/dot8mIF50Z