Sorry for delays in reply... I will try to answer questions here...
Martijn - yes - it is best to install CalCheck on a workstation that has Outlook installed - it does not need to be installed on the server.
Brian - no - this tool does not cover PF Calendars. It only looks at the default Calendar folder for mailboxes.
For the error below (SJB) - it looks like the tool was run in server mode? If so - then you could open the individual log for that recipient to see what failed...
Bala - to run the tool in server mode - the account/profile being used must have Full Mailbox access to the mailboxes on the server.
Also - I have been asked a couple times why the tool was failing to log into a specific mailbox when using the "-m" switch to specify opening a specific other mailbox. When using the "-m" switch, you must use the legacyExchangeDN of the other mailbox - not the AD DN.
Thanks for all the comments!
-randy