You can offer them the filtered html code that Pub 2007 produces and see if
that will work, but Publisher does not produce W3C standards compliant code.
You can produce the code as an index.htm file along with an index_files
folder which contains all the supporting graphics. You can also go to Tools
Options > Web tab and uncheck the option of using the supporting folder. I
think Spike's suggestion to use a .mht file might be your best choice for
your use. It is a self-contained, single page website that can be inserted
into some email. Ask the company if that will work.
Also be aware that Pub 2007 features email merge, and you might be able to
do your own marketing. It is a bit finicky though.
DavidF