private void WriteMHTHeader()
{
StringBuilder sb = new StringBuilder(256);
string s = "=?utf-8?B?" + System.Convert.ToBase64String(Encoding.UTF8.GetBytes(FileName)) + "?=";
sb.Append("From: ").AppendLine(s);
sb.Append("Subject: ").AppendLine(s);
sb.Append("Date: ").AppendLine(ExportUtils.GetRFCDate(DateTime.Now));
sb.AppendLine("MIME-Version: 1.0");
sb.Append("Content-Type: multipart/related; type=\"text/html\"; boundary=\"").Append(FBoundary).AppendLine("\"");
sb.AppendLine();
sb.AppendLine("This is a multi-part message in MIME format.");
sb.AppendLine();
ExportUtils.Write(Stream, sb.ToString());
}