send email failed

Question

How can i send email to multiple clients located in different domains such hotmail,yahoo,and gmail
is it required to provide Smpt server name, if we have multipe domain id, what should we do?
I am using fowling code but getting exception failed.
MailMessage mailMsg = new MailMessage();
            mailMsg .From = "[email protected]";
            mailMsg .To = "[email protected]";
            mailMsg .Cc = "[email protected]"";
            mailMsg .Bcc = "[email protected]";
            mailMsg .Subject = "SubjectOfTheMailString";
            mailMsg .Body = "BodyOfTheMailString";
            SmtpMail.Send(mailMsg ); 
Thanks,