I'm not sure if my issue is the same. Back on Oct 25, 2016 I received the the last .eml in Mac Mail that would show. On the 28th of Oct. the same file came as "Mail Attachment.eml" They both were sent to me from the same PC. Since then, all of these emails from the same sender come as the above .eml file.
The issue: I can not open, save or view the .eml file. I have tried to rebuild the mailbox, tried dragging it MailRaider, tried sending to a gmail account; nothing works.
When I try to view, I get the spinning icon, When I try to drag to desktop, I get the circle with slash, When I try to right click and save, nothing happens - no window will open for me to select a place to save to.
As you can see by the date of October, I have been fighting this for awhile. Yes, I can walk to the front office and print out the offending email but why? Why am I no longer able to see these files? I switched to Sierra when it came available. and am now on 10.12.2 My mail is on 10.2 (3259)
BTW, not sure if it matters but the .eml is a multi level form sent to the PC from one of our customers that they fill in the fields and I would be able to copy/paste from those field into my program. Now that it doesn't work anymore, It's manual typing from the printed copy.
Please let me know if I need to provide additional information for you to understand the issue better or just let me know I have the wrong forum...
Thank you in advance for any assistance you may provide.