Email message header provides a list of technical details about the message, such as who sent it, the software used to compose it and the email servers that it passed through on it’s way to the recipient.

One of the most useful pieces of information in the header is the IP address of the originating server, which can be used to determine why the legitimate email went to Junk E-mail folder or why your email did not go through.

1. Open the message in a new window in Outlook.
2. Select View | Options... from the message's menu.

All header lines appear under Internet Headers at the bottom of the dialog that comes up.