How to encode subject content when sending mail with TIdMessage ?

Today, I tried to develop mail application with TIdMessage, but I have problem in character set encoding. And I found the answer at http://www.yac.com.pl/mt.texts.tidmessage.charset.en.html

With this wrapper class, 

  TMyMessage = class(TIdMessage)
  private
    procedure InitializeUTF8(
                var VTransferHeader: TTransfer; var VHeaderEncoding: char; var VCharSet: string);
  end;
  
  procedure TMyMessage.InitializeUTF8(
    var VTransferHeader: TTransfer; var VHeaderEncoding: char; var VCharSet: string);
  begin
    VCharSet := 'UTF-8';
  end;

And then,

  LMessage := TMyMessage.Create(NIL);
  LMessage.ContentType := 'text/plain; charset=UTF-8';
  LMessage.OnInitializeISO := LMessage.InitializeUTF8;

Actually CharSet property of TIdMessage should work fine, but it doesn't work.

On Delphi 2009, some features are changed so you need to use below wrapper class as below.
 

  TMyMessage = class(TIdMessage)
  private
    procedure InitializeUTF8(
                var VHeaderEncoding: char; var VCharSet: string);
  end;

procedure TMyMessage.InitializeUTF8(
    var VHeaderEncoding: char; var VCharSet: string);
  begin
    VCharSet := 'UTF-8';
  end;