Sending of executable files (.exe, .msi, .bat, etc) through our email systems has been restricted per University Information Security to protect your mailbox and Harvard's network resources from being damaged by email-borne viruses and malware.
Your colleagues and collaborators should be able to send you documents, spreadsheets, PDFs and the like through email without impediment, but other types of files may be quarantined for further inspection if the system cannot automatically determine whether they pose security threats.