Outlook does not permit the automatic download of pictures in email messages as a security measure to help prevent possible spamming. It does permit images from sites in your Trusted Zone to show but blocks all others. Using the steps in this tutorial, you can override this feature.
Before you begin the steps below, open your Outlook account.
1. Click Tools.
2. Select Trust Center.
3. In the left pane, select Automatic Download.
4. In the right pane, uncheck the Don’t download pictures automatically in HTML e-mail messages or RSS items checkbox.
5. Click OK.
Note: These steps only work for Outlook 2007. For previous versions, you will need to follow the tutorial described here.