After you compose a message and send it, the message is processed by the e-mail server at your Internet service provider (ISP). If the message is for someone who does not have a mailbox on your e-mail server, the server forwards the message to another e-mail server. The message is forwarded from server to server. It may go through several e-mail servers until it reaches the e-mail 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 used to compose it, and the e-mail servers it passed through on its way to the recipient. You can use these details to identify problems with the e-mail message or help discover the sources of unsolicited commercial e-mail messages.

Steps to view this data:

  1.     Open a message.
  2.     On the Message tab, in the Options group (2007) or Tags group (2010/2013), click the Dialog Box Laucher Icon image (arrow in the bottom right hand corner).
In the Message Options dialog box, the headers appear in the Internet headers box.