MailMessage Help

Question

Hi.
I am trying to setup email in a webapp I am working on.  Here is the code I have so far:

public void SendReminderEmail(System.Web.HttpContext context, string emailSubject, string emailTo, string emailFrom, string emailBody, string SMTPServer)

{

System.Net.Mail.MailAddress mailTo = new System.Net.Mail.MailAddress(emailTo);

System.Net.Mail.MailAddress mailFrom = new System.Net.Mail.MailAddress(emailFrom);

System.Net.Mail.MailMessage message = new System.Net.Mail.MailMessage(mailFrom, mailTo);

message.IsBodyHtml = true;

message.Subject = emailSubject;

message.Body = emailBody;

System.Net.Mail.SmtpClient smtpClient = new System.Net.Mail.SmtpClient(SMTPServer);

smtpClient.Send(message);

}

protected void SendEmail_Click(object sender, EventArgs e)

{

string emailSubject = "Test Subject";

string emailTo = "Will put an email address in here.";

string emailFrom = "Will put an email address in here";

string emailBody = "Test Email";

string SMTPServer = "Will put an smtp server in here;

this.SendReminderEmail(this.Context, emailSubject, emailTo, emailFrom, emailBody, SMTPServer);

}

So when the adminstrator clicks the button, it is going to fire off an email to a group of people.  The problem I have is that I am getting this error:

"Mailbox name not allowed. The server response was: Sorry, that domain isn't in my list of allowed rcpthosts."

And it points to the line,  smtpClient.send(message)

When I run it, I actually have email addresses and an smtpOut server in there. I just didn't include them in here for security sake.  Anyone have an idea what is causing that error?
Thanks.