How to View the Complete Email Message Source in Outlook

Outlook takes messages it receives from the internet and stores the headers and individual message parts independently from the message body. When you select a message, Outlook collects the pieces to show just what is needed. Except when you want Outlook to display the headers. By default, Outlook removes certain header lines. Here's how to configure Outlook to preserve the complete source of email messages.

Instructions in this article apply to Outlook 2019, Outlook 2016, Outlook 2013, Outlook 2010, and Outlook for Microsoft 365.

Make Available the Complete Message Source in Outlook

To configure Outlook to retrieve the original source of messages as they were received at any time:

Open Registry Editor. Go to the Windows Search box, enter regedit, and press Enter. Or, right-click the Windows Start button, select Run, enter regedit, and select OK.

Navigate to the folder of the Windows Registry for your version of Microsoft Outlook:

Outlook 2019 and 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

Go to the Edit tab, select New, then choose either DWORD or QWORD:
- Choose DWORD (32-bit) Value if you have a 32-bit version of Office.
- Choose QWORD (64-bit) Value if you have a 64-bit version of Office.
To name the value, enter SaveAllMIMENotJustHeaders and press Enter.
Double-click the SaveAllMIMENotJustHeaders value.
In the Value data text box, enter 1, then press OK.
Close Registry Editor.
Open Outlook. If Outlook is open, close and then re-open it.

Outlook stores the message source and the message content. This means that future emails will take more space. Because PST files (where Outlook stores mail) have a size limit, regularly delete or archive email in Outlook.

See the Complete Source of a Message

To 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):