I don't know - are you just talking about attaching one word document to one
Yahoo! e-mail? if so, you probably need to save your document to disk then
use whatever feature Yahoo! mail (I don't have it) provides to let you add a
file as an attachment. If you're talking about merging to Yahoo! mail with
one attachment per e-mail, you can't do that with Word "out of the box" as
far as I know. If there is a way to create Yahoo! emails programmatically
you might be able to do /something/ but I don't know what facilities Yahoo!
offers in that area, if any.

Peter Jamieson