How to View the Complete Email Message Source in Outlook

Email & Messaging

Updated October 04, 2018

A "normal" email client stores messages as it receives them—with all the header lines and the body, separated by a blank line. With its Exchange background and a complicated local storage system, Outlook does this a bit differently.

Outlook Takes Internet Emails Apart

Outlook takes messages it receives from the internet apart as soon as it sees them. It stores the headers independently from the message body and breaks out the individual message parts, too. When it needs a message, Outlook collects the pieces to show just what is needed. You can have it display all the headers, for example.

Unfortunately, the original message structure is lost, though. Even when you save the message to disk as an .msg file, Outlook only saves a slightly modified version (the Received: header lines are stripped, for example).

Fortunately, you can tell Outlook to preserve the complete source of internet messages, though. How Outlook operates will not change, but you can retrieve the original source of messages as they were received at any time.

PST Size Will Increase!

Outlook will store the message's source in addition to storing the message's content. This means future emails will take up roughly double the space. Since PST files (where Outlook stores mail) do have a size limit, make sure you do judiciously archive email in Outlook (or delete outright). By the way, you typically can recover deleted emails.

Make Available the Complete Message Source in Outlook

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

Open Registry Editor.

The quickest way is to execute regedit from the Run box. The link above walks you through that process if you've never done that before.

Next you'll need to navigate to a specific areas of the Windows Registry but this differs based on the version of Microsoft Outlook you're running:

Outlook 2016:

HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\Options\Mail.

Outlook 2013:

HKEY_CURRENT_USER\Software\Microsoft\Office\15.0\Outlook\Options\Mail

Outlook 2010:

HKEY_CURRENT_USER\Software\Microsoft\Office\14.0\Outlook\Options\Mail

Outlook 2007:

HKEY_CURRENT_USER\Software\Microsoft\Office\12.0\Outlook\Options\Mail

Outlook 2003:

HKEY_CURRENT_USER\Software\Microsoft\Office\11.0\Outlook\Options\Mail

From the menu in Registry Editor, select Edit followed by New, followed by either DWORD or QWORD:
- Select DWORD (32-bit) Value if you have a 32-bit version of Office
- Select QWORD (64-bit) Value if you have a 64-bit version of Office
Name the value as the following, and then press Enter to save:
```
SaveAllMIMENotJustHeaders
```
Double-click the newly created SaveAllMIMENotJustHeaders value.
As the Value data, enter 1 and then press OK.
Close Registry Editor.
Open Outlook, or close and then re-open it if it's been running.

See the Complete Source of a Message in Outlook 2016, 2013, & 2010

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 and then double-click the email.
Choose 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 2007 & 2003

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.