physics101 writes: It appears that Microsoft have made changes in the way that the email headers are formed for the mail sent from hotmail accounts. The X-Originating-Email tag now points to the IP belonging to Microsoft instead of the sender's IP. There are numerous threads (e.g. this one) at answers.microsoft.com. MS representatives are claiming that "the issue has already been forwarded to our Escalation team for further investigation". Despite of the bunch of dissatisfied users, this answer is being offered time and the time again for over two months. It suspiciously looks like a policy change for which they don't want to give any explanation.