Opening file in Illustrator prompts "Text Import Options" and does not open file correctly.

Question

I've been dealing with this issue for quite a while and I am thoroughly stumped. A co-worker has emailed me .ai files in the past without issue. In the last couple months, however, her attached .ai files no longer open properly.
This is the first screen I get when trying to open the files:
Regardless of what checkboxes are marked or options changed, the outcome is always the same:
If you can't read that, the error code is as follows:
{"Body":{"ErrorCode":500,"FaultMessage":"Unable to get write stream for mac attachment.","IsTransient":false}}
Putting this line of code into Google returns exactly "0" finds.
Nobody else in the company seems to have an issue with opening the same file when this co-worker forwards it to them. I did notice, however, that the file is 141 kb within her email, but when I download it, it shrinks to 344 bytes. I don't know if for whatever reason my computer is just not downloading all of the information or what might be going on.
To reiterate, these are the facts that I know:
1. She is on a mac and I am on a PC.
2. We are both using Illustrator CS6.
3. Other co-workers on PCs do not have this problem when she emails it to them.
4. The file shrinks from 141 kb to 344 bytes when I try to download it from her email.
Edit: I just had her send the email to my personal gmail account and the file opened perfectly, so this appears to be an issue with office365.com which is where my business email is located. Everyone else here uses the same email service, however, so this is still an isolated issue with my account.
Any help or ideas would be very much appreciated.
Thank you!

Answer 1

Thank you for the reply. We went through a lot of different ideas to try and fix this, but zipping the file never even crossed our minds for some reason... :\