I think most of us have given up objecting. I'm not sure whether they still
do it, but at one time Microsoft, via their web-based user-interface, used
to invite users to post attachments, so it became pointless for us to try to
persuade users not to do something when Microsoft was encouraging them to do
it. But I think you'll find that most of us will not open an attachment -
and I would strongly advise anyone else not to open one, or at the very
least, not to open it without saving it to disk and running your virus
checker on it first.
