Email message headers provide technical details about the message. These details can include who sent the message, the software that was used to compose it, and the email servers that it passed through on its way to the recipient.
About message headers
After a message is sent, it is processed by an email server that is used by your organization or Internet service provider (ISP). If the message is for someone who doesn’t have an account on the same email server, the message is forwarded to another email server. Frequently, the message passes through several email servers until it reaches the email server on which the recipient of the message has a mailbox.
From the time when the message is first created, information about it is added to a hidden section of the message known as the Internet header. The information includes technical details, such as who created the message, the software that was used to compose it, and the email servers it passed through on its way to the recipient. These details can identify problems with the message or help discover the sources of junk email, also known as spam.
As spam techniques become more sophisticated, the inclusion of false information in message headers is a growing problem. This is also known as spoofing. For example, a message might indicate that it is from Anne Weiler at Contoso (firstname.lastname@example.org) when it is actually from a bulk email service that promotes schemes to get rich quickly. Therefore, before you send a complaint response to someone about his or her message, remember that the header information might be forged. The person whom you think sent the message might not be the actual sender.
View message headers
Open the message in its own window.
On the File tab, select Properties.
Header information appears in the Internet headers box.