Why I can't send or receive some files via email attached to the message?
Forbidden file extensions for certain file types by email clients or email servers
The following file extensions are not allowed by many email clients or email servers. Messages including attachments with these extensions are blocked by default to view/open or cannot be sent or received - in most cases, executable file types: .BAT, .COM, .CMD, .EXE, .HTA, .LNK, .PIF, .SCR, .SHS, .VB*, .CPL and many other. For more information visit section and file type category: Email attachment blocked file types or potentially dangerous and malicious file types here at File-Extensions.org website.
Additional security information to email attachments
Also, never open files with a “dot-3 dot-3” ending (examples: “filename.doc.pif” and “filename.xls.com”)
Some emails have more than one file attached. One or two of the attached files may “look” okay. For example, they may end in “doc” or “ppt” which leads you to think they are legitimate Word or Powerpoint files. But......if there is also one of the forbidden 3-letter-ending files attached to the email, do not open any of the files attached to that email (even the ones that “look” okay)!
You may be less suspicious about certain e-mails because they come from a friend, or someone you know. If they have one of these forbidden files attached, they did not really come from your friend and it is a spam email message. Some nefarious virus has more than likely hijacked your friend's address book and used it to create e-mails that “look like” they were sent from your friend.
If you are unsure whether or not an attachment you have received is a virus, please do not open nor forward the attachment. Call for assistance and for the safety of your computer and your data use some of Internet and antivirus security suites available.