Open Email client on Cleints Machine

I am using vb.net 2008. I have a page with a gridview with names and emails.
When the client clicks a row I want to open the clients default email with the
To field and Subject Field populated. I use the code below but it looks like it opens the
default email client on the server not on the clients machine.
Dim theStringBuilder As New System.Text.StringBuilder()
        theStringBuilder.Append("mailto:" & gvMembers.SelectedRow.Cells(4).Text)
        theStringBuilder.Append("&subject=")
        theStringBuilder.Append("")
        System.Diagnostics.Process.Start(theStringBuilder.ToString())
How do you open the email client on the clients amchine?

Thanks