function After(Src: string; S: string):string;
var
  F: Word;
begin
  F:= Pos(Src, S);
  if F = 0 then
      After:= ''
  else
      After:= Copy(S, F+Length(Src), Length(S));
end;

  tmp := '1232$$23423432';

  showmessage(Before('$$',tmp));
  showmessage(after('$$',tmp));

function SplitString(const source, ch: string): TStringList;
var
  temp, t2: string;
  i: integer;
begin
  result := TStringList.Create;
  temp := source;
  i := pos(ch, source);
  while i <> 0 do
  begin
    t2 := copy(temp, 0, i - 1);
    if (t2 <> '') then
      result.Add(t2);
    delete(temp, 1, i - 1 + Length(ch));
    i := pos(ch, temp);
  end;
  result.Add(temp);
end;

procedure TForm1.Button1Click(Sender: TObject);
var
 st : TStringList;
begin
  st := SplitString('xxx@hoho.com', '@');
  showmessage(st[1]);
end;