Apple Mail 2.x (Mac)

  1. Select the message you want to view the headers of.
  2. Press SHIFT-COMMAND-H to toggle full headers for the message. (Alternatively you can click VIEW in the menu bar, click MESSAGE, click LONG HEADERS.

Microsoft Outlook 2003 (Win)

  1. Select the message you want to view the headers of.
  2. Right click the mouse, select OPTIONS
  3. Headers will be displayed within the "Internet Headers" area of a pop-up window.

Mozilla Thunderbird 2.x (Win)

  1. Select the message you want to view the headers of.
  2. Press CTRL-U (or click VIEW from the menu bar, select MESSAGE SOURCE)
  3. Headers will be displayed in a new window.

Google Mail (GMail)

  1. Open the message you want to view the headers of.
  2. Click the down arrow next to the "Reply" link.
  3. Select "Show Original" to open a new window with the full headers

Windows Live Hotmail

(Full Version)
  1. This does not work with Safari on Mac OS X
  2. Right click on the message. (From the list of emails)
  3. Select "View Source"
  4. A new window with the full headers and HTML source of the email will open

Yahoo Mail

"New" Version
  1. Right click on the message.
  2. Select "View Full Headers"
  3. A new window with the full headers will open

Yahoo Mail

"Classic" Version
  1. Click on the message.
  2. Click "Full Headers" on the bottom right of the screen