MailMessage m = new MailMessage();
m.From = GetSetting("mail_sender");
m.To = GetSetting("mail_receiver");
m.Subject = "Экспорт из " + GetSetting("branch_namer");
m.Body = "см. вложение";
m.BodyFormat = MailFormat.Text;
m.BodyEncoding = System.Text.Encoding.GetEncoding(1251);
SmtpMail.SmtpServer = GetSetting("smtp_address");
String smtpLogin = GetSetting("smtp_login");
if (smtpLogin.Trim() != String.Empty)
{
  m.Fields.Add("http://schemas.microsoft.com/cdo/configuration/smtpauthenticate", 1); 
  m.Fields.Add("http://schemas.microsoft.com/cdo/configuration/sendusername", smtpLogin); 
  m.Fields.Add("http://schemas.microsoft.com/cdo/configuration/sendpassword", GetSetting("smtp_password")); 
}
m.Attachments.Add(new MailAttachment(resFile, MailEncoding.Base64));
SmtpMail.Send(m);