As you can view the embedded image in GroupWise, other web based email but not in Outlook client which appear the issue is relate to Outlook client settings.
Remote Image inserter solution use a special technique by adding image as background which lets the image not to add as attachments to the message. You can view the sent message source in GroupWise client to get more information.
You can try the following Outlook settings to enable message background images.
The Outlook client’s (2003 and 2007) automatic download settings block pictures in HTML messages. If the HTML message contains background images then Outlook client will not display these images unless you turn off “Don’t download pictures or other content automatically in HTML e-mail” checkbox.
In Outlook 2003, see the Tools – Options – Security – “Change Automatic Download settings” for more information.
In Outlook 2007, click Tools, then Trust Center to open the Trust Center. In the left Trust Center pane, click Automatic download.
See the article for more information: http://office.microsoft.com/en-us/outlook/HP073107391033.aspx
Hope this helps. Please let us know how you go.