When a user accepts or declines a forwarded meeting invitation in a Microsoft Exchange Server 2013 environment, the accept or decline message is sent to the forwarder instead of to the meeting organizer.
For example, user A sets a rule to forward all messages to user B. When the organizer sends a meeting invitation to both user A and user B, user B receives two invitations. Regardless of which invitation user B accepts or declines, the response is sent to user A instead of to the meeting organizer.
This issue occurs because the Inbox forwarding rule can't preserve the original organizer in Exchange Server 2013.