I would like to understand the differences between a vanilla openxchange and the version used in the 1&1 MailXchange.

According to the information in the About menu 1&1 is running the following version
1&1 MailXchange 4.0
GUI Version: 6.22.3 Rev4
Server Version: 7.2.2-Rev20

The following features are not working at 1&1 but are working in the openxchange online demo at http://www.open-xchange.com/get-started.html#c289
1) It is not possible to give access to email folders to other users

2) When I send invitations from the MailXchange GUI or via Outlook the invited people only get emails like
"Sie wurden von ox-test1 zu einem Ereignis eingeladen:
12:00 - 13:00
Dienstag, 8. Oktober 2013

without any ics-attachment (there is no possibility to accept/reject etc) and no entry is made in the calendar.

3) The out of office reply function which is available at the "1&1 MailXchange Connector" menu of Outlook is grayed out.

Is the 1&1 MailXchange based on an too old version of openxchange? Any change that 1&1 will support the missing features?