I will present a "strange" situation. Some of the users are receiving blank e-mails without any sender name, recipient, data, subject, etc. When I look in Microsoft Outlook at Options to see the Internet Headers, at "Received: from" only the IP address is there (no email address). I localized the IP addresses in countries we don't have commercial partnerships, so it's becoming more stranger. My question is what is the purpose of this activity, how our users emails addresses had been disclosed knowing that they are used for business purposes (personally I don't send emails outside company) and if this messages could be blocked at an Exchange box level.