Ask the sender to:
Rename the attachment to docname.ext.rename.rename where docname.ext is the original name of the attachment including the extension. Send the attachment again (with this new name) and a personal message to you.
When you receive this new message with the attachment, you will need to:
Download the attachment.
Scan it with your virus checker.
Rename it. (Windows: right click on the file and select Rename. You need to delete the part of the name that says ".rename" or ".rename.rename".)