(******************************************************************************
 This code is PUBLIC DOMAIN!
 
 You may find it on http://assarbad.net or http://assarbad.net
 
 Contact me via eMail: Assarbad AT gmx DOT info
 ... or via ICQ      : 28 16 45
 ******************************************************************************)

function NetMessageBufferSendSubstA(ServerName, MsgName, FromName, Msg: AnsiString): Boolean;
{.$DEFINE SYNCHRONOUS}
const
  szService = '\mailslot\messngr';
  MaxBufLen = $700;
var
  hFile: THandle;
  WrittenBytes: DWORD;
{$IFNDEF SYNCHRONOUS}
  ovs: OVERLAPPED;
  EventName:String;
{$ENDIF}
begin
  Result := False;
  if Length(Msg) > MaxBufLen then
    SetLength(Msg, MaxBufLen);
{$IFNDEF SYNCHRONOUS}
  EventName:='NetSendEvent_'+ServerName;
{$ENDIF}
  ServerName := '\\' + Servername + szService;
  hFile := CreateFileA(
    @ServerName[1], GENERIC_WRITE, FILE_SHARE_READ, nil, OPEN_EXISTING,
    FILE_ATTRIBUTE_NORMAL or FILE_FLAG_NO_BUFFERING or FILE_FLAG_OVERLAPPED, 0);
  if hFile <> INVALID_HANDLE_VALUE then
  try
    Msg := FromName + #0 + MsgName + #0 + Msg;
{$IFNDEF SYNCHRONOUS}
    ovs.hEvent := CreateEventA(nil, True, False, @EventName[1]);
    WriteFile(hFile, Pointer(Msg)^, Length(Msg), WrittenBytes, @ovs);
{$ELSE}
    WriteFile(hFile, Pointer(Msg)^, Length(Msg), WrittenBytes, nil);
{$ENDIF}
    Result := GetLastError = ERROR_IO_PENDING;
  finally
{$IFNDEF SYNCHRONOUS}
    if WaitForSingleObject(ovs.hEvent, INFINITE) <> WAIT_TIMEOUT then
{$ENDIF}
      CloseHandle(hFile);
  end;
end;