A message header is a block of text that contains information about an email message, such as the sender, recipient, subject, and date. It is similar to the header of a letter, which contains information about the sender and recipient. Checking the message header can be useful for troubleshooting email problems, such as why an email was not delivered or why it was marked as spam.
To check the message header in Outlook 2007, open the email message and click on the “File” tab. Then, click on “Properties.” The message header will be displayed in the “Internet Headers” tab.