Not receiving email from a particular sender

I have a client that is trying to send an attachment (.doc text file), but is getting an error message from the inmotion server. The automated response reads "This message has been rejected because it has a potentially executable attachment "Mail Attachment.eml". This form of attachment has been used by recent viruses or other malware."
I am new to inmotion and haven't had a problem like this previously with this sender or others.
The rejection email suggests zipping the files, but this sender isnt so tech-abled. I have received unzipped files from others without a problem, is there something on my end that I can do to receive these attachments?
Thanks
dc