internal void PrepareHeaders(bool sendEnvelope, bool allowUnicode) { string headerName; if (_headersEncoding == null) { _headersEncoding = Encoding.GetEncoding(MimeBasePart.DefaultCharSet); } //ContentType is written directly to the stream so remove potential user duplicate Headers.Remove(MailHeaderInfo.GetString(MailHeaderID.ContentType) !); Headers[MailHeaderInfo.GetString(MailHeaderID.MimeVersion)] = "1.0"; // add sender to headers first so that it is written first to allow the IIS smtp svc to // send MAIL FROM with the sender if both sender and from are present headerName = MailHeaderInfo.GetString(MailHeaderID.Sender) !; if (Sender != null) { Headers.InternalAdd(headerName, Sender.Encode(headerName.Length, allowUnicode)); } else { Headers.Remove(headerName); } headerName = MailHeaderInfo.GetString(MailHeaderID.From) !; Headers.InternalAdd(headerName, From !.Encode(headerName.Length, allowUnicode)); headerName = MailHeaderInfo.GetString(MailHeaderID.To) !; if (To.Count > 0) { Headers.InternalAdd(headerName, To.Encode(headerName.Length, allowUnicode)); } else { Headers.Remove(headerName); } headerName = MailHeaderInfo.GetString(MailHeaderID.Cc) !; if (CC.Count > 0) { Headers.InternalAdd(headerName, CC.Encode(headerName.Length, allowUnicode)); } else { Headers.Remove(headerName); } headerName = MailHeaderInfo.GetString(MailHeaderID.ReplyTo) !; if (ReplyTo != null) { Headers.InternalAdd(headerName, ReplyTo.Encode(headerName.Length, allowUnicode)); } else if (ReplyToList.Count > 0) { Headers.InternalAdd(headerName, ReplyToList.Encode(headerName.Length, allowUnicode)); } else { Headers.Remove(headerName); } Headers.Remove(MailHeaderInfo.GetString(MailHeaderID.Bcc) !); if (_priority == MailPriority.High) { Headers[MailHeaderInfo.GetString(MailHeaderID.XPriority)] = "1"; Headers[MailHeaderInfo.GetString(MailHeaderID.Priority)] = "urgent"; Headers[MailHeaderInfo.GetString(MailHeaderID.Importance)] = "high"; } else if (_priority == MailPriority.Low) { Headers[MailHeaderInfo.GetString(MailHeaderID.XPriority)] = "5"; Headers[MailHeaderInfo.GetString(MailHeaderID.Priority)] = "non-urgent"; Headers[MailHeaderInfo.GetString(MailHeaderID.Importance)] = "low"; } //if the priority was never set, allow the app to set the headers directly. else if (((int)_priority) != -1) { Headers.Remove(MailHeaderInfo.GetString(MailHeaderID.XPriority) !); Headers.Remove(MailHeaderInfo.GetString(MailHeaderID.Priority) !); Headers.Remove(MailHeaderInfo.GetString(MailHeaderID.Importance) !); } Headers.InternalAdd(MailHeaderInfo.GetString(MailHeaderID.Date) !, MailBnfHelper.GetDateTimeString(DateTime.Now, null) !); headerName = MailHeaderInfo.GetString(MailHeaderID.Subject) !; if (!string.IsNullOrEmpty(_subject)) { if (allowUnicode) { Headers.InternalAdd(headerName, _subject); } else { Headers.InternalAdd(headerName, MimeBasePart.EncodeHeaderValue(_subject, _subjectEncoding, MimeBasePart.ShouldUseBase64Encoding(_subjectEncoding), headerName.Length)); } } else { Headers.Remove(headerName); } EncodeHeaders(_headers !, allowUnicode); }