You can accept or decline appointments, all day events, and tasks that are sent from Internet-enabled collaboration clients. Some of these clients include Microsoft Exchange, Lotus Notes, and Macintosh iCal.
Open the appointment, task, or reminder note.
Click Accept or Decline on the toolbar.
or
Click the down-arrow to the right of the button to select an Accept level of availability, or to select Decline with Options.
(Optional) If you selected Decline with Options, you can type a comment, and then click OK.
If the item is an Auto-Date item, click This Instance to accept or decline this single Auto-Date item, or click All Instances to accept or decline all instances of the Auto-Date item.
By default, a message is sent to the sender of the item, indicating the action you took.
In addition, you can right-click the Internet item and select Import Calendar. This creates a new calendar and imports the item to the new calendar.