Can TNEF be avoided using MAPI? - delphi

Question

I am using this code to send emails through MAPI using Delphi.
A few users who use Microsoft mailing software report that the receipants receive emails with an attachment WinMail.dat. I know that this is an issue with Microsoft Exchange/Outlook and can be corrected by disabling RTF/TNEF. (I don't know for sure because I do not use Microsoft mailing software).
My question is, if I can tell the mailing software to not use TNEF using the MAPI.
function SendEMailUsingMAPI(const Subject, Body, FileName, SenderName, SenderEMail, RecipientName, RecipientEMail: string): Integer;
var
Message: TMapiMessage;
lpSender, lpRecipient: TMapiRecipDesc;
FileAttach: TMapiFileDesc;
SM: TFNMapiSendMail;
MAPIModule: HModule;
FileType: TMapiFileTagExt;
begin
// Source: http://www.stackoverflow.com/questions/1234623/how-to-send-a-mapi-email-with-an-attachment-to-a-fax-recipient
// Modified
FillChar(Message,SizeOf(Message),0);
if (Subject <> '') then begin
Message.lpszSubject := PChar(Subject);
end;
if (Body <> '') then begin
Message.lpszNoteText := PChar(Body);
end;
if (SenderEmail <> '') then
begin
lpSender.ulRecipClass := MAPI_ORIG;
if (SenderName = '') then begin
lpSender.lpszName := PChar(SenderEMail);
end
else begin
lpSender.lpszName := PChar(SenderName);
end;
lpSender.lpszAddress := PChar('smtp:'+SenderEmail);
lpSender.ulReserved := 0;
lpSender.ulEIDSize := 0;
lpSender.lpEntryID := nil;
Message.lpOriginator := #lpSender;
end;
if (RecipientEmail <> '') then
begin
lpRecipient.ulRecipClass := MAPI_TO;
if (RecipientName = '') then begin
lpRecipient.lpszName := PChar(RecipientEMail);
end
else begin
lpRecipient.lpszName := PChar(RecipientName);
end;
lpRecipient.lpszAddress := PChar('smtp:'+RecipientEmail);
lpRecipient.ulReserved := 0;
lpRecipient.ulEIDSize := 0;
lpRecipient.lpEntryID := nil;
Message.nRecipCount := 1;
Message.lpRecips := #lpRecipient;
end
else begin
Message.lpRecips := nil;
end;
if (FileName = '') then begin
Message.nFileCount := 0;
Message.lpFiles := nil;
end
else begin
FillChar(FileAttach,SizeOf(FileAttach),0);
FileAttach.nPosition := Cardinal($FFFFFFFF);
FileAttach.lpszPathName := PChar(FileName);
FileType.ulReserved := 0;
FileType.cbEncoding := 0;
FileType.cbTag := 0;
FileType.lpTag := nil;
FileType.lpEncoding := nil;
FileAttach.lpFileType := #FileType;
Message.nFileCount := 1;
Message.lpFiles := #FileAttach;
end;
MAPIModule := LoadLibrary(PChar(MAPIDLL));
if MAPIModule = 0 then begin
Result := -1;
end
else begin
try
#SM := GetProcAddress(MAPIModule,'MAPISendMail');
if #SM <> nil then begin
Result := SM(0,Application.Handle,Message,
MAPI_DIALOG or MAPI_LOGON_UI,0);
end
else begin
Result := 1;
end;
finally
FreeLibrary(MAPIModule);
end;
end;
if Result <> 0 then begin
raise Exception.CreateFmt('Error sending eMail (%d)', [Result]);
end;
end;

Answer 1

Not in Simple MAPI. If you were using Outlook Object Model or Extended MAPI, you could set a special MAPI property on the message before sending it to disable TNEF format.