Received mail attachments acting weird
Some emails I've received lately show attachments as a dotted line box with an arrow inside. If I try to detach them, nothing happens. If I click on the arrow, the dotted line box with the arrow changes to a regular Word doc icon but with the word "downloading" underneath, and that never ends. I never had this problem until a few days ago. As an aside, for a month, Mail never quits until I do a force quit, but I can live with that. I can't live with not being able to detach and look at my attachments. I'd appreciate any help.
iMac, macOS High Sierra (10.13.5), Mid-2011