"Error validating user [user name] while processing calendar appointment"
Copy the user name in question from the console. It must be copied exactly as it appears you do not need the hierarchy portion just the common name.
If this user doesn't exist in the address book, then the error is self evident. If you are certain this is a valid user, do the following to verify the error. Open their mail file and go to the calendar, click on the meetings view, this should show all the user's meeting documents with out the calendar GUI. On the Notes tool bar click on "View" select "Search bar". Type or paste (preferred) the name you copied from the Notes console in the search field and click on the search button. This should show all the meeting documents causing the error message. Right click on any of the documents and click on the "Fields Tab" (Triangle) this will show all the fields in the document. Find the $Busyname field here you will find that the user's name does not match with their person document in the address book.
You can delete these documents o fix them with the code provided. The code is for an agent, I call it "Fix Meetings Docs" but you can call it anything you like. Do not make it a shared agent, the users might run it and damage something in their mail file. It should be set to "Run Manually from Actions Menu" and run on "Selected Documents" only...
Once you have created this agent in the user's mail file it should be available from the "Actions" menu. Go back to the Meetings view in the calendar and do a search for the wrong name. select all the "bad" documents and click on "Actions" then select the agent you just created. This will go through all the documents and replace the $Busyname field with the name you placed in the agent, in the example I used it is:
You would replace this with the correct, cannonical, user name for the mail file...
Code: FIELD $BusyName := $BusyName;
Owner := "CN=Charles Thompson/OU=ATL/O=ASSURANT/C=US";
This was first published in January 2001