Not all email you receive can be trusted. Viewing full message headers allows you to see 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 its way to the recipient. This information is often needed by security and support specialists to help locate the source of spam or other specific email issues.
So, how email works? After you compose a message and send it, the message is processed by the email server at your Internet Service Provider (ISP). If the message is for someone who does not have a mailbox on your email server, the server forwards the message to another -mail server. The message is forwarded from server to server. It may go 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 email header. The information includes technical details, such as who created the message, the software used to compose it, and the email servers it passed through on its way to the recipient. You can use these details to identify problems with the email message or help discover the sources of unsolicited commercial email messages.
How to view the email headers
Every client has a different way how to display email headers:
Outlook for Windows: Double click the message to open it in a new window. Select the File tab, and then click Properties. The data is next to Internet headers.
Outlook Express, Windows Mail, or Windows Live Mail (Windows): In the message index, right-click the message, and then select Properties. Click the Details tab.
Outlook for Mac OS X: In your Inbox (or other folder), right-click or control-click the message, and then select View Source.
Thunderbird (Windows, Mac OS X): Click View, select Headers, and then choose All.
Opera Mail: Open an email. Right click on the message body and choose View All Headers and Messages.
Mail (Mac OS X): With the message selected, from the View menu, select Message, and then select either All Headers or Long Headers.
Gmail: Open an email. Click the down arrow next to Reply, at the top of the message pane and select Show Original.
Yahoo Mail: Open an email. Click More and then View Full Header.
Live Mail, Hotmail, Outlook.com: Right click the message you’d like to view headers for and select View Message Source.
AOL: Open an email. In the Action menu, select View Message Source.
Excite Webmail: Open an email. Click the View Full Headers icon located on the right of the From: line.
Outlook Web App (OWA): Open an email. Click the options icon (three dots near the top right), and then click View Message Details.
I hope that this article helped you to understand how to display email headers. Feel free to share your thoughts about this article using the comments section below or catch us on Twitter.