I'm having the same problem. I put names on the approved senders list, and e-mails still came with a notice that it was a prohibited file type and was deactivated. All my attachments are deactivated and I can't get them back.
I did what Microsoft's website said to do going into the security settings, but the settings only were all or nothing. I was not willing to allow every type of attachment to come to my computer, but I do still want to get the attachments I used to be able to receive. What has changed? According to Microsoft all my updates are current. PLEASE HELP