Предполагам, че CommandTimeout:=0 не е желателно да го използваш, макар че върши работа...

аз използва следния код, може да е модификация на нещо което си срещал, но върши работа, поне при мен...

procedure TForm1.Button4Click(Sender: TObject);

var

  MemStream: TMemoryStream;



  StrSQL, ConnectionString: string;

  RecordSet: _RecordSet;



  RecordsAffected: olevariant;

  ImgActualSize: integer;

  lngOffset, iSize: integer;

  Data: olevariant;

  P:    PByteArray;



begin



  MemStream := TMemoryStream.Create;



  ImageTarget.Picture.Bitmap.SaveToStream(MemStream);



  MemStream.Seek(0, 0);





  StrSQL := 'SELECT ENTRYID, IMAGE_DATA FROM MAIL_USERS WHERE ENTRYID={00000001-0000-0000-0000-000000000000}';

  ConnectionString :=

    'Provider=Microsoft.Jet.OLEDB.4.0;Password="";Data Source=C:\IMIADOAB.mdb';





  Recordset := CoRecordset.Create;





  Recordset.Open(StrSQL, ConnectionString, adOpenKeyset,

    adLockOptimistic, adCmdText);



  Data := VarArrayCreate([0, 4095], varByte);



  iSize := 4096;

  repeat





    P := VarArrayLock(Data);

    FillChar(P^, iSize, 0);



    iSize := MemStream.Read(PByte(P)^, 4096);

    VarArrayUnlock(Data);



    if iSize > 0 then

    begin



      if iSize < 4096 then

        VarArrayReDim(Data, iSize - 1); // must trim to the exact size

      Recordset.Fields.Item['IMAGE_DATA'].AppendChunk(Data);

      // append chunk to parameter object

    end; // if





  until iSize < 4096;



  Data := Unassigned;

  Recordset.Update(EmptyParam, EmptyParam);



  Recordset := nil;





  MemStream.Free;



end;