Cannot accept calendar invite

[Clarify]

We have recently upgraded to v4 and have noticed that we are having issues when accepting invitations sent from an external domain.

The invite comes through as an attachment and in the attachment you cannot accept or decline the meeting, the buttons are disabled. (see attachments)

I'm pretty sure that these problems are being caused by the new version of NoD.

We don't have this problem when sending invites internally.
I can't find and option that specifically mentions outlook calendars.

Can anyone help?

[Marcos]

Does disabling integration with Outlook make a difference? Try the following:
1, close Outlook
2, open the EAV GUI and press F5 to open the setup
3, go to Miscellaneous -> Email client integration
4, untick the "Integrate into Microsoft Outlook" checkbox
5, start Outlook