I’ve run into the same problem. Some of the responses in user groups have been to change the Internet settings in the Location doc to “Notes with Internet Explorer” save and exit the Location doc, then change the settings back to “Microsoft Internet Explorer”. I tried this and it worked on one email, but that was it. We are still trouble-shooting it and have been looking at various MIME settings both on the server (e.g. format of the message set in the Person doc) and within the Client preferences. I even totally uninstalled and reinstalled the Client in case it was a file issue but without any success.
We think we may have found the cause and are testing at the moment to see if it’s caused by the Internet proxy server. If the user forwards me the email when I’m set to bypass the proxy, then I get the images, if I don’t bypass the proxy I get the image holders instead. We’re testing a new proxy server in a few weeks so have been stalling users until then.
I hope this helps.

The problem is that the perweb.nsf database is missing. When you switch the browser to Notes with IE and open an HTML formated mail the database is created. At that point you can switch the browser back to just IE.

Or you can rollout a copy of perweb.nsf to everyone.