emails not delivered & not bouncing back

I have a user who is sending emails and has confirmed they are not getting delivered and they do not bounce back. Is this possible? If she sends to the same address using her hotmail account the emails go through.

We are using Outlook 97 and Microsoft Mail internally which doesn’t work to well. We have a Satellite for an internet connection which sucks. So our smtp server is set to smtp.direcway.com and our pop3 server is a local company. I assume any problems sending email is with the smtpserver and I get zero support from LinCsat (Canadian provider) the first thing they tell me to do is disconnect the network.