View Outlook Source Code for messages

Make Available the Complete Message Source in Outlook

To set up Outlook so you can see the complete source of emails:

    Press Windows-R
    Type "regedit".
    Hit Enter.
    For Outlook 2013:
        Go to HKEY_CURRENT_USER\Software\Microsoft\Office\15.0\Outlook\Options\Mail
    For Outlook 2010:
        Go to HKEY_CURRENT_USER\Software\Microsoft\Office\14.0\Outlook\Options\Mail
    For Outlook 2007:
        Go to HKEY_CURRENT_USER\Software\Microsoft\Office\12.0\Outlook\Options\Mail
    For Outlook 2003
        Go to HKEY_CURRENT_USER\Software\Microsoft\Office\11.0\Outlook\Options\Mail
 
   Select Edit | New | DWord (32bit) from the menu.
    Type "SaveAllMIMENotJustHeaders".
    Hit Enter.
    Double-click the newly created SaveAllMIMENotJustHeaders value.
    Type "1".
    Click OK.
    Close the registry editor.
    Restart Outlook if it has been running.

See the Complete Source of a Message in Outlook

Now you can retrieve the source of newly retrieved POP messages (editing the SaveAllMIMENotJustHeaders value does not restore the complete message source for emails that were already in Outlook):

    Open the desired message in its own window.
        Double-click the email.
    Click FILE.
    Make sure the Info category is open.
    Now click Properties.
    Find the source to the email under Internet headers:.
    Click Close.

See the Complete Source of a Message in Outlook 2003/7

To open a message's full source in Outlook 2003 and Outlook 2007:

    Click on the desired message with the right mouse button in the Outlook mailbox.
    Select Options... from the menu.
    Find the message source under the (now improperly named) Internet headers: section.