That's a perverse way to do it! What if the user doesn't have Word installed? What if they they don't have this mythical "email" mode within Word? What if they use a different email client? Etc.
And the reason you can't use
Process.Start
to launch Word is because your code is running
on the server. Even if Word is installed on the server, it would open on the server, where nobody would be able to see it.
What's wrong with a straight
mailto:
link?
string subject = "Look at this page";
string url = "http://www.codeproject.com/Questions/1094998/How-do-I-get-the-word-file-opened-dynamically-that";
string body = "Please visit this page\n" + url;
hyperlink.NavigateUrl = string.Format("mailto:?subject={0}&body={1}",
HttpUtility.UrlEncode(subject),
HttpUtility.UrlEncode(body));
<a href="mailto:?subject=Look%20at%20this%20page&body=Please%20visit%20this%20page%0Ahttp%3A%2F%2Fwww.codeproject.com%2FQuestions%2F1094998%2FHow-do-I-get-the-word-file-opened-dynamically-that">Send a link</a>
Send a link
You can't specify an HTML body, but most email clients automatically turn URLs into hyperlinks in plain-text messages.