Developer, Former MVP, now at Microsoft - Best of 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013
Following up from my post about Sending Outlook Invites here is a shorter one on how to respond.
BTW, two of my outlook rules are relevant to invites.
The first one auto-marks as read the ACCEPT responses if there is no comment in the body of the accept (I check later who has accepted and who hasn't via the "Tracking" button of the invite). I don’t have a rule for the DECLINE and TENTATIVE cause typically I follow up with folks that send those.
The second rule ensures that all Invites go to a specific folder. That is the first folder I see when I triage email. It is also the only folder which I have configured to show a count of all items inside it, rather than the unread count - when sending a response to an invite the item disappears from the folder and hence it is empty and not nagging me.