repeat
        LThePart := LParts.Items[LTextPart];
        if (LThePart.FSize <> 0) then begin
          Break;
        end;
        Inc(LTextPart);
      until LTextPart >= LParts.Count - 1;

function TForm1.TryGetBodyStrOnly(const AUIDStr: String; var ABodyStr: String): Boolean;
var
  i: Integer;
  ATextPartNumStr: String;
  AStream: TStream;
  AnIdImapMsgParts: TIdImapMessageParts;
  AnIdImapMsgPart: TIdIMapMessagePart;
  ACntEnc, ACntCharSet: String;
begin
  Result := False;
  ABodyStr := '';
  ATextPartNumStr := '';
  ACntEnc  = '';

  AnIdIMapMsgParts := TIdImapMessageParts.Create(nil);
  try
    if not id_IMAP.UIDRetrieveStructure(AUIDStr, AnIdIMapMsgParts) then
    begin
      DoLog('UIDRetrieveStructure failed', True, True, False, True);
      Exit;
    end;

    for i := 0 to AnIdIMapMsgParts.Count - 1 do
    begin
      AnIdImapMsgPart := AnIdImapMsgParts.Items[i];
      if (AnIdImapMsgPart.BodyType.ToUpper = 'TEXT') and (AnIdImapMsgPart.BodySubType.ToUpper = 'PLAIN') then
      begin
        ATextPartNumStr := AnIdImapMsgPart.ImapPartNumber;
        ACntEnc         := AnIdImapMsgPart.ContentTransferEncoding;
        ACntCharSet     := AnIdImapMsgPart.CharSet;
        Break;
      end;
    end;
  finally
    AnIdImapMsgParts.Free;
  end;

  if ATextPartNumStr = '' then
  begin
    DoLog('Text part not exists', False, True, True, True);
    Result := True;
    Exit;
  end;

  AStream := TStringStream.Create;
  try
    if not id_IMAP.UIDRetrievePart(AUIDStr, ATextPartNumStr, AStream, ACntEnc) then
    begin
      (* UIDRetrievePart sometimes return data in first line of response like this [1 FETCH (FLAGS (\Seen $NotJunk) UID 123 BODY[1] "SomeData")].
         In this case UIDRetrieve returned False whereas we excepted response like [1 FETCH (FLAGS (\Seen $NotJunk) UID 123 BODY[1] {8}] *)
      DoLog('UIDRetrievePart failed', True, True, False, True);
      Exit;
    end;

    Result := True;

    ABodyStr := (AStream as TStringStream).DataString;
    if (ACntCharSet.ToUpper = 'UTF-8') then
      ABodyStr := UTF8ToString(RawByteString(ABodyStr))
    else
      DoLog(Format('Unsupported charset:"%s" with encoding:"%s"', [ACntCharSet, ACntEnc]), False, True, True, True);
  finally
    AStream.Free;
  end;
end;