Sending MailMessage SMTP

I expect that I am missing something quite simple.  This line, "MailMessage mail = new MailMessage();"  raises an error:

 FormatException was unhandled by user code
The specified string is not in the form required for an e-mail address.
using System;

using System.Collections;

using System.Configuration;

using System.Data;

using System.Web;

using System.Web.Security;
...