unit Unit1;

interface

uses
 Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, FileCtrl, ActiveX, ShlObj, ComObj, Vcl.Buttons;

type
  TForm1 = class(TForm)
    SpeedButton2: TSpeedButton;
    procedure SpeedButton2Click(Sender: TObject);
  private
    { Private declarations }
  public

  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

function GetFileListDataObject(const Directory: string; Files:
  TStrings):
  IDataObject;
type
  PArrayOfPItemIDList = ^TArrayOfPItemIDList;
  TArrayOfPItemIDList = array[0..0] of PItemIDList;
var
  Malloc: IMalloc;
  Root: IShellFolder;
  FolderPidl: PItemIDList;
  Folder: IShellFolder;
  p: PArrayOfPItemIDList;
  chEaten: ULONG;
  dwAttributes: ULONG;
  FileCount: Integer;
  i: Integer;
begin
  Result := nil;
  if Files.Count = 0 then
    Exit;
  OleCheck(SHGetMalloc(Malloc));
  OleCheck(SHGetDesktopFolder(Root));
  OleCheck(Root.ParseDisplayName(0, nil,
    PWideChar(WideString(Directory)),
    chEaten, FolderPidl, dwAttributes));
  try
    OleCheck(Root.BindToObject(FolderPidl, nil, IShellFolder,
    Pointer(Folder)));
    FileCount := Files.Count;
    p := AllocMem(SizeOf(PItemIDList) * FileCount);
    try
      for i := 0 to FileCount - 1 do
      begin
        OleCheck(Folder.ParseDisplayName(0, nil,
                 PWideChar(WideString(Files[i])), chEaten, p^[i],
                 dwAttributes));
      end;
      OleCheck(Folder.GetUIObjectOf(0, FileCount, p^[0], IDataObject,
        nil,
        Pointer(Result)));
    finally
      for i := 0 to FileCount - 1 do
      begin
        if p^[i] <> nil then
          Malloc.Free(p^[i]);
      end;
      FreeMem(p);
    end;
  finally
    Malloc.Free(FolderPidl);
  end;
end;



procedure TForm1.SpeedButton2Click(Sender: TObject);
var
  SelFileList: TStrings;
  I: Integer;
  DataObject: IDataObject;
  Effect: Integer;
  CLSID_SendMail: TGUID;
  DT: IDropTarget;
  P: TPoint;

begin
  CLSID_SendMail := StringToGUID('{9E56BE60-C50F-11CF-9A2C-00A0C90A90CE}');
  with TOpenDialog.Create(self) do
  try
    SelFileList := TStringlist.Create;
    if Execute then
    begin
      SelFileList.Add(FileName);
      SelFileList.Add(FileName);
      SelFileList.Add(FileName);
      DataObject := GetFileListDataObject(ExtractFilePath(FileName), SelFileList);
      Effect := DROPEFFECT_NONE;
      CoCreateInstance(CLSID_SendMail, nil, CLSCTX_ALL, IDropTarget, DT);
      DT.DragEnter(DataObject, MK_LBUTTON, P, Effect);
      DT.Drop(DataObject, MK_LBUTTON, P, Effect);
    end;
  finally
    free;
    SelFileList.Free;
  end;
end;

end.