Here’s a scenario that I ran into with a customer recently.
You’re a developer that's using the CDO 1.21 Session’s SetOption method to set the "FreeBusyMonths" and have setting it with a value of 36. However, after some time, some of your users are reporting that they are seeing that it looks like the max of the Free/Busy information that is published is 12 months. Further inspection indicates that anything over 12 months does not seem to be published, even though you are specifically setting this option to 36 in your application.
For more background, let's look at the following article to help explain CDO 1.21’s SetOption method and what can be set and retrieved with it:
MSDN Documentation : SetOption Method (Session Object)
So in my example. I specifically used the SetOption method to set the “FreeBusyMonths” to 36 months and created a recurring appointment with no end date. I then looked at the Free/Busy data from an Outlook client and noticed that we did not see any Free/Busy data being published past the 1 year point.
So what gives?
After some research, what is actually happening here is the following:
CDO will allow you to use SetOption method to set the “FreeBusyMonths” OptType to whatever you want, meaning there is no limits on what you can set for the Free/Busy Publishing months. But, as we know from the articles below, CDO acts like a client and will create the Free/Busy message in the Public Folder, much like Outlook does.
The following articles explain CDO 1.21’s role with regards to Free/Busy publishing.
XADM: CDO Changed to Regenerate Public Free-and-Busy Message
XCLN: CDO Only Publishes Three Months of Free/Busy Data
The problem occurs when CDO goes through its logic internally to create the Free/Busy message, as it has to do here to be a good client, it will actually enforce a 12 month Free/Busy publishing limit.
So the information noted above in the MSDN is still valid, but doesn’t mention that there are other things that occur under the covers with CDO 1.2x with regards to the actual publishing of Free/Busy data.