1. Information Security
  2. Interpreting Email Headers

Interpreting Email Headers

If you have contacted IT support for help with a spam or other email-related issue, you may have been asked to provide full header information for the email in question.

Full email headers are more than the “From” and “To” lines your email client displays at the top of your messages. The full email headers contain a lot of information, including every hop a message has taken across the Internet to get from its sender to you. This data can be very valuable in tracking down the real origin of an email. Email can be forged fairly easily, but every email will always be marked with the true IP address of the sending computer. The trick is getting your email client to display these lines so that you can analyze them yourself or forward them to your support staff.

Full Email Header Sample

sample complete email header

Incomplete Email Header Sample

sample incomplete email header

How to Display Full Email Headers

Office 365 Webmail (Outlook Web Access)
  1. Double-click the message in your inbox to open it.
  2. On the top menu where you see buttons for delete, reply, etc., click the button with an ellipsis (…) on it.
  3. Click View Message Details.
Outlook 2007 / 2010 (Windows)
  1. Double-click the message in your inbox to open it.
  2. From the File menu, click Properties. The headers will display in the Internet Headers section of the Properties window that appears.
Outlook 2011 / 2013 (Mac)
  1. From your inbox, command click (right click) the message and choose View Source.
  2. The headers will be opened in TextEdit.
Apple Mail
  1. Double-click the message in your inbox to open it.
  2. From the View menu, click Message, then All Headers. The headers will then display at the top of the message.
Gmail
  1. Open the message.
  2. Click the small downward-facing arrow next to the Reply button at the top right of the message.
  3. Select Show Original and the headers will appear in a new window.
Other Email Clients
View headers in other email clients.

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