Web Forms :: Send Mail Error / When Throw Code To The Server,programm Throws An Exeption?

Following problem occurred:
sending mail error

code for sending mail:

private void SendMail (string from, string to, string subj, string body, string dom)
{
System.Net.Mail.MailMessage mm = new System.Net.Mail.MailMessage ();
mm.From = new System.Net.Mail.MailAddress (from);
mm.To.Add (new System.Net.Mail.MailAddress (to));
mm.Subject = subj;
mm.IsBodyHtml = true;
mm.Body = body;
System.Net.Mail.SmtpClient client = new System.Net.Mail.SmtpClient (dom);
client.Send (mm);
}

error (exeption):

The server has violated protocol Server Response: <some code> // was translated from russian

if I test on my computer, everything works perfectly When I throw code to the server,programm throws an exeption