An image in an HTML-formatted email message is not displayed in Outlook 2013 when you use a proxy server that is configured to use basic authentication

  • Article
  • Applies to:
    Outlook 2013

Original KB number:   2846350

Symptoms

Consider the following scenario:

  • You have a computer that is running Microsoft Outlook 2013.
  • You access the Internet by using a proxy server that is configured to use basic authentication.
  • You use Outlook 2013 to open an HTML-formatted email message.
  • The HTML-formatted email message contains an HTTP reference to an image that requires proxy authentication.

In this scenario, you are not prompted for authentication, and the image is not displayed.

Resolution

To resolve this issue, follow these steps:

  1. Select Start, select Run, type regedit in the Open box, and then select OK.

  2. Locate and then select the following registry subkey:
    HKEY_CURRENT_USER\Software\Microsoft\Office\15.0\Common

  3. On the Edit menu, point to New, and then select DWORD (32-bit) Value.

  4. Type AllowImageProxyAuth, and then press Enter.

  5. In the Details pane, right-click AllowImageProxyAuth, and then select Modify.

  6. In the Value data box, type 1 or 2, and then select OK.

  7. Exit Registry Editor.

Note

  • If you set the value to 1 in step 6, you are prompted for authentication one time per Outlook session in the scenario that is described in the Symptoms section. If you cancel the authentication request, you are not prompted again during that Outlook session. This option introduces a small volume of network overhead per Outlook session.
  • If you set the value to 2 in step 6, you are prompted for authentication when it is required. Typically you are prompted for authentication one time per Outlook session. However, in some scenarios, you may be prompted multiple times. For example, if you cancel the authentication request for one image, you are prompted again for the next image that requires proxy authentication. This option introduces additional network overhead for each downloaded image. If an email message contains multiple images, the additional network overhead may cause slow performance in Outlook.
  • If the value in step 6 is nonexistent, or if you set the value to 0, you are not prompted for authentication, and the image might not be displayed.