I'm not sure this still works, but at one time you could use a nested
mergefield like the following to achieve this effect:

{ QUOTE { INCLUDEPICTURE http://www.mysite.com/myimage.jpg
\*MERGEFORMATINET \d } }

All the {} need to be the special field braces you can insert using ctrl-F9.
That may work if you just want to send a link to a single image (i.e. all
the e-mails link to the same image). If you need each e-mail to link to a
different image, you /may/ be able to replace the URL by a mergefield
containing the URL, e.g.

{ QUOTE { INCLUDEPICTURE "{ MERGEFIELD picureURL }"
\*MERGEFORMATINET \d } }

You may also have to uncheck WOrd Tools|Options|General|Web
Options|Files|Update links on save.

Peter Jamieson