Hi there My query is actually two fold (both with regards to calender). Firstly regarding the question in the subject - I found a post on Apple forums discussing this whereby a user was advised to edit the ITIP.stings file in the contents of the iCal.app to change the standard message that states "To accept or decline this invitation, click the link below" etc message that an Outlook user received when getting a calender invite from MAC Calender. The post is here: https://discussions.apple.com/thread/1365089 Problem is, on Mavericks it does not have that string in that file - I've actually checked ALL the .strings files in that folder but to no avail. Did it move somewhere else on Mavericks? On another note...this whole process is part in part moving from Entourage to Mac Mail and Calender due to Apple's (illogical) removal of the ability to sync with anything other than iCal / Mail / iCloud. So we manually moved everything across (thousands of mails and hundreds of folders) and hundreds and hundreds of calender events. Now its syncing but herewith the problem...if I create an event and send it to someone, they receive it as the iCloud account email and not our work email (pop account with our own domain). Even then when I open it in Outlook, it has some horribly malformed address and when you accept, you get a delivery failure. After researching this, we have to create a different Calender (On the Mac) and this sends 100% (except for the message in the body we'd like to change) but this does not sync with the Iphone or the iPad. Then we have to manually change the calender event to the iCloud calender and it brings up a message that its going to send the update to all the attendees...and you must choose between send via mail or send via server. What do I do!? This all worked perfectly fine using Entourage 2008 but as we know, this cannot be used anymore for syncing of any kind.