My objective is to create a "to do" out of an email message. However, when I open a message the check mark icon for doing this is greyed out. I am getting a message that says the, "to do calendar is unvailable until you add the selected account to iCal."
Do you have your system set up so that iCal is connected to Exchange to view your calendar? If not, that's probably what the message is referring to. Go to the Accounts pane of the iCal preferences and if your Exchange account isn't listed (it works only with Exchange 2007), add it there.
Unfortunatley, this is not the problem. In fact, the exchange account is listed.
Something else maybe worth noting -- on the left hand pane, where the folders are listed, I see my corporate folder, underneath that are two sub-folders -- Calendar and Tasks. One would think that the Task subfolder is what the system message was referring to...no?
Sorry, I can't be of further help. I've seen other reports that To Do creation in Mail doesn't work with Exchange 2007, and I've not found anyone posting a solution. Perhaps someone else here will be able to provide suggestions.